diff --git a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/OptitrackStreamingClientEditor.cs b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/OptitrackStreamingClientEditor.cs
index 8c05238e6..9d414b9e4 100644
--- a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/OptitrackStreamingClientEditor.cs	
+++ b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/OptitrackStreamingClientEditor.cs	
@@ -16,6 +16,7 @@ public class OptitrackStreamingClientEditor : Editor
     private VisualElement runtimeOffline;
     private VisualElement runtimeOnline;
     private VisualElement runtimeInfo;
+    private Label runtimeActionText;
 
     public override VisualElement CreateInspectorGUI()
     {
@@ -36,10 +37,11 @@ public class OptitrackStreamingClientEditor : Editor
         runtimeOffline = root.Q("runtimeOffline");
         runtimeOnline = root.Q("runtimeOnline");
         runtimeInfo = root.Q("runtimeInfo");
+        runtimeActionText = root.Q<Label>("runtimeActionText");
 
         var reconnectBtn = root.Q<Button>("reconnectBtn");
         if (reconnectBtn != null)
-            reconnectBtn.clicked += () => { if (Application.isPlaying) client.Reconnect(); };
+            reconnectBtn.clicked += () => RunPlayModeAction("Full reconnect requested", () => client.Reconnect());
 
         root.schedule.Execute(UpdatePlayModeState).Every(300);
 
@@ -83,9 +85,21 @@ public class OptitrackStreamingClientEditor : Editor
             SetStatusStyle(null);
             if (statusText != null)
                 statusText.text = "Stopped";
+            if (runtimeActionText != null)
+                runtimeActionText.text = "";
         }
     }
 
+    private void RunPlayModeAction(string message, System.Action action)
+    {
+        if (!Application.isPlaying || client == null)
+            return;
+
+        action?.Invoke();
+        if (runtimeActionText != null)
+            runtimeActionText.text = message;
+    }
+
     private void SetStatusStyle(bool? connected)
     {
         if (statusDot == null || statusText == null) return;
diff --git a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uss b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uss
index 341187de0..721d03195 100644
--- a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uss	
+++ b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uss	
@@ -95,6 +95,13 @@
     background-color: #b45309;
 }
 
+.opti-runtime-action {
+    font-size: 11px;
+    color: #fbbf24;
+    -unity-font-style: bold;
+    margin-bottom: 4px;
+}
+
 .opti-runtime-info {
     padding: 4px 0;
 }
diff --git a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uxml b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uxml
index c85e656a0..c8916dc07 100644
--- a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uxml	
+++ b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/Editor/UXML/OptitrackStreamingClientEditor.uxml	
@@ -41,6 +41,20 @@
         </ui:Foldout>
     </ui:VisualElement>
 
+    <!-- Connection Health -->
+    <ui:VisualElement class="section">
+        <ui:Foldout text="Connection Health" value="true" class="section-foldout">
+            <uie:PropertyField binding-path="ConnectionHealthCheckIntervalSeconds" label="Health Check Interval"/>
+            <uie:PropertyField binding-path="StreamingFrameTimeoutSeconds" label="Frame Timeout"/>
+            <uie:PropertyField binding-path="FullReconnectInitialDelaySeconds" label="Full Reconnect Initial Delay"/>
+            <uie:PropertyField binding-path="FullReconnectFrameWaitSeconds" label="Full Reconnect Frame Wait"/>
+            <uie:PropertyField binding-path="FullReconnectRetryDelaySeconds" label="Full Reconnect Retry Delay"/>
+            <uie:PropertyField binding-path="DirectServerInfoTimeoutMs" label="Server Info Timeout Ms"/>
+            <uie:PropertyField binding-path="DirectModelDefTimeoutMs" label="MODELDEF Timeout Ms"/>
+            <ui:HelpBox message-type="Info" text="Reconnect refreshes direct NatNet server info and MODELDEF before rebuilding the local receiver. Lower timeouts make reconnect more responsive when the command channel is unavailable."/>
+        </ui:Foldout>
+    </ui:VisualElement>
+
     <!-- Definition Refresh -->
     <ui:VisualElement class="section">
         <ui:Foldout text="Definition Refresh" value="true" class="section-foldout">
@@ -72,7 +86,8 @@
                 <ui:HelpBox message-type="Info" text="Runtime controls are available in Play Mode."/>
             </ui:VisualElement>
             <ui:VisualElement name="runtimeOnline" class="opti-runtime-online">
-                <ui:Button name="reconnectBtn" text="OptiTrack Reconnect" class="opti-reconnect-btn"/>
+                <ui:Button name="reconnectBtn" text="Full Reconnect" class="opti-reconnect-btn"/>
+                <ui:Label name="runtimeActionText" class="opti-runtime-action"/>
                 <ui:VisualElement name="runtimeInfo" class="opti-runtime-info"/>
             </ui:VisualElement>
         </ui:Foldout>
diff --git a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackSkeletonAnimator_Mingle.cs b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackSkeletonAnimator_Mingle.cs
index 52b3a327f..1f26919c6 100644
--- a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackSkeletonAnimator_Mingle.cs	
+++ b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackSkeletonAnimator_Mingle.cs	
@@ -47,8 +47,8 @@ public class OptitrackSkeletonAnimator_Mingle : MonoBehaviour
     public float interpolationDelay = 0f;
 
     private OptitrackSkeletonDefinition m_skeletonDef;
+    private int m_boundSkeletonDefinitionId = -1;
     private string previousSkeletonName;
-
     private OptitrackStreamingClient m_boundStreamingClient;
 
     [HideInInspector]
@@ -295,10 +295,19 @@ public class OptitrackSkeletonAnimator_Mingle : MonoBehaviour
         RebindStreamingClient();
     }
 
+    public void RefreshSkeletonDefinitionBinding()
+    {
+        if (StreamingClient == null)
+            InitializeStreamingClient();
+
+        RebindStreamingClient();
+    }
+
     private void RebindStreamingClient()
     {
         m_boundStreamingClient = StreamingClient;
         m_skeletonDef = null;
+        m_boundSkeletonDefinitionId = -1;
         m_boneIdToMappingIndex.Clear();
         m_snapshotPositions.Clear();
         m_snapshotOrientations.Clear();
@@ -314,6 +323,7 @@ public class OptitrackSkeletonAnimator_Mingle : MonoBehaviour
         m_skeletonDef = StreamingClient.GetSkeletonDefinitionByName(SkeletonAssetName);
         if (m_skeletonDef != null)
         {
+            m_boundSkeletonDefinitionId = m_skeletonDef.Id;
             RebuildBoneIdMapping();
             isSkeletonFound = true;
         }
@@ -595,18 +605,21 @@ public class OptitrackSkeletonAnimator_Mingle : MonoBehaviour
         {
             if (StreamingClient != null)
             {
-                m_skeletonDef = StreamingClient.GetSkeletonDefinitionByName(SkeletonAssetName);
+                OptitrackSkeletonDefinition latestDef = StreamingClient.GetSkeletonDefinitionByName(SkeletonAssetName);
 
-                if (m_skeletonDef != null)
+                if (latestDef != null)
                 {
+                    bool definitionChanged = latestDef.Id != m_boundSkeletonDefinitionId;
+                    m_skeletonDef = latestDef;
                     OptitrackSkeletonState skelState = StreamingClient.GetLatestSkeletonState(m_skeletonDef.Id);
                     bool wasFound = isSkeletonFound;
                     isSkeletonFound = (skelState != null);
 
-                    if (isSkeletonFound && !wasFound)
+                    if (isSkeletonFound && (!wasFound || definitionChanged))
                     {
                         StreamingClient.RegisterSkeleton(this, SkeletonAssetName);
                         previousSkeletonName = SkeletonAssetName;
+                        m_boundSkeletonDefinitionId = m_skeletonDef.Id;
                         RebuildBoneIdMapping();
                         Debug.Log($"[OptiTrack] 스켈레톤 '{SkeletonAssetName}' 연결 성공");
                     }
@@ -622,6 +635,8 @@ public class OptitrackSkeletonAnimator_Mingle : MonoBehaviour
                 {
                     // 스켈레톤 정의를 찾지 못함 → 지수 백오프로 재조회 요청 빈도 제한
                     isSkeletonFound = false;
+                    m_skeletonDef = null;
+                    m_boundSkeletonDefinitionId = -1;
                     m_definitionRefreshRequests++;
 
                     // 처음 3회까지는 즉시 요청, 이후 백오프 적용
diff --git a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackStreamingClient.cs b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackStreamingClient.cs
index d10f83912..954a87f5d 100644
--- a/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackStreamingClient.cs	
+++ b/Assets/External/OptiTrack Unity Plugin/OptiTrack/Scripts/OptitrackStreamingClient.cs	
@@ -123,6 +123,9 @@ public class OptitrackSkeletonDefinition
     /// <summary>Skeleton asset name.</summary>
     public string Name;
 
+    /// <summary>True when the definition was inferred from frame packets and does not contain a Motive asset name.</summary>
+    public bool IsSynthetic;
+
     /// <summary>Bone names, hierarchy, and neutral pose position information.</summary>
     public List<BoneDefinition> Bones;
 
@@ -348,6 +351,35 @@ public class OptitrackStreamingClient : MonoBehaviour
     [Tooltip("Automatically retries the initial connection and reconnects when streaming frames stop.")]
     public bool AutoReconnect = true;
 
+    [Header("Connection Health")]
+    [Tooltip("How often connection health is checked. This only reads local timestamps and does not contact Motive.")]
+    [Min(0.1f)]
+    public float ConnectionHealthCheckIntervalSeconds = 0.25f;
+
+    [Tooltip("Seconds without live/replay frames before the stream is considered stale.")]
+    [Min(0.5f)]
+    public float StreamingFrameTimeoutSeconds = 1.0f;
+
+    [Tooltip("Delay before the first full reconnect attempt after a stale stream is detected.")]
+    [Min(0f)]
+    public float FullReconnectInitialDelaySeconds = 0.0f;
+
+    [Tooltip("Seconds to wait for frames after a full reconnect attempt before retrying.")]
+    [Min(0.25f)]
+    public float FullReconnectFrameWaitSeconds = 1.5f;
+
+    [Tooltip("Delay before subsequent full reconnect attempts.")]
+    [Min(0.5f)]
+    public float FullReconnectRetryDelaySeconds = 2.0f;
+
+    [Tooltip("Timeout for the direct NatNet server-info command during connect/reconnect, in milliseconds.")]
+    [Min(100)]
+    public int DirectServerInfoTimeoutMs = 500;
+
+    [Tooltip("Timeout for the direct NatNet MODELDEF command during connect/reconnect, in milliseconds.")]
+    [Min(100)]
+    public int DirectModelDefTimeoutMs = 1000;
+
     [Tooltip("Changes to the version of Natnet used by the server")]
     public string ServerNatNetVersion = "";
     public string ClientNatNetVersion = "";
@@ -385,6 +417,11 @@ public class OptitrackStreamingClient : MonoBehaviour
     private int m_directTimeoutCount = 0;
     private bool m_directNatNetConnected = false;
     private bool m_directNoModelDefWarned = false;
+    private IPAddress m_directServerAddress = null;
+    private IPAddress m_directLocalAddress = null;
+    private IPAddress m_directMulticastAddress = null;
+    private UInt16 m_directCommandPort = 0;
+    private UInt16 m_directDataPort = 0;
 
     private NatNetClient m_client;
     private NatNetClient m_replayClient;
@@ -426,6 +463,7 @@ public class OptitrackStreamingClient : MonoBehaviour
 
     /// <summary>Maps from a streamed skeleton names to its component.</summary>
     private Dictionary<string, MonoBehaviour> m_skeletons = new Dictionary<string, MonoBehaviour>();
+    private HashSet<MonoBehaviour> m_registeredSkeletonComponents = new HashSet<MonoBehaviour>();
 
     /// <summary>Maps from a streamed trained markerset names to its component.</summary>
     private Dictionary<string, MonoBehaviour> m_tmarkersets = new Dictionary<string, MonoBehaviour>(); // trained markerset added
@@ -445,7 +483,16 @@ public class OptitrackStreamingClient : MonoBehaviour
     /// <summary>Cache from streamed asset ID to asset name.</summary>
     private Dictionary<Int32, string> m_assetIdToNameCache = new Dictionary<Int32, string>();
 
+    private HashSet<Int32> m_latestFrameRigidBodyIds = new HashSet<Int32>();
+    private HashSet<Int32> m_currentFrameRigidBodyIds = new HashSet<Int32>();
+    private HashSet<Int32> m_latestFrameSkeletonIds = new HashSet<Int32>();
+    private HashSet<Int32> m_currentFrameSkeletonIds = new HashSet<Int32>();
+    private bool m_hasFrameRigidBodyTopologySnapshot = false;
+    private bool m_hasFrameSkeletonTopologySnapshot = false;
+
     private volatile bool m_pendingDefinitionRefresh = false;
+    private volatile bool m_forceDefinitionRefreshSoon = false;
+    private volatile bool m_pendingSkeletonDefinitionNotify = false;
     private float m_definitionRefreshCooldown = 0f;
 
     private bool m_isReconnecting = false;
@@ -473,8 +520,39 @@ public class OptitrackStreamingClient : MonoBehaviour
         m_pendingDefinitionRefresh = true;
     }
 
+    private bool CanRefreshDefinitions()
+    {
+        return !SkipDataDescriptions &&
+               (m_client != null || (ConnectionType == ClientConnectionType.Multicast && m_directNatNetConnected));
+    }
+
+    private void RefreshDefinitionsForActiveTransport()
+    {
+        if (m_client != null)
+        {
+            UpdateDefinitions();
+            ResubscribeRegisteredAssets();
+            return;
+        }
+
+        if (ConnectionType == ClientConnectionType.Multicast && m_directNatNetConnected)
+        {
+            UpdateDirectDefinitions();
+            ResubscribeRegisteredAssets();
+            return;
+        }
+
+        throw new InvalidOperationException("No active OptiTrack transport is available for DataDescription refresh.");
+    }
+
     private void Update()
     {
+        if (m_pendingSkeletonDefinitionNotify)
+        {
+            m_pendingSkeletonDefinitionNotify = false;
+            NotifyRegisteredSkeletonDefinitionsChanged();
+        }
+
         if (m_directFrameLogPending)
         {
             m_directFrameLogPending = false;
@@ -683,14 +761,20 @@ public class OptitrackStreamingClient : MonoBehaviour
             m_latestTMarkMarkerSpheres.Clear();
         }
 
+        if (m_forceDefinitionRefreshSoon)
+        {
+            m_forceDefinitionRefreshSoon = false;
+            m_pendingDefinitionRefresh = true;
+            m_definitionRefreshCooldown = 0f;
+        }
+
         // Refresh streamed asset definitions when Motive actors or rigid bodies are added/removed.
-        if (m_pendingDefinitionRefresh && m_definitionRefreshCooldown <= 0f && m_client != null && !SkipDataDescriptions)
+        if (m_pendingDefinitionRefresh && m_definitionRefreshCooldown <= 0f && CanRefreshDefinitions())
         {
             m_pendingDefinitionRefresh = false;
             try
             {
-                UpdateDefinitions();
-                ResubscribeRegisteredAssets();
+                RefreshDefinitionsForActiveTransport();
                 m_definitionRefreshCooldown = Mathf.Max(DefinitionRefreshInterval, 1f);
                 m_nextAutoDefinitionRefreshTime = Time.unscaledTime + Mathf.Max(DefinitionRefreshInterval, 1f);
             }
@@ -706,8 +790,7 @@ public class OptitrackStreamingClient : MonoBehaviour
             m_definitionRefreshCooldown -= Time.deltaTime;
 
         if (AutoRefreshDefinitions &&
-            m_client != null &&
-            !SkipDataDescriptions &&
+            CanRefreshDefinitions() &&
             m_definitionRefreshCooldown <= 0f &&
             Time.unscaledTime >= m_nextAutoDefinitionRefreshTime)
         {
@@ -780,13 +863,7 @@ public class OptitrackStreamingClient : MonoBehaviour
             return;
         }
 
-        if (m_directNatNetConnected && ConnectionType == ClientConnectionType.Multicast)
-        {
-            Debug.Log(GetType().FullName + ": direct UDP receiver is already active; reconnect request skipped.", this);
-            return;
-        }
-
-        Debug.Log("OptiTrack: reconnect requested.");
+        Debug.Log("OptiTrack: full reconnect requested.");
 
         OnDisable();
 
@@ -795,7 +872,7 @@ public class OptitrackStreamingClient : MonoBehaviour
 
     /// <summary>
     /// Coroutine for handling the reconnection process with a retry loop.
-    /// Attempts up to 5 times: 1s delay on first attempt, 5s on subsequent.
+    /// Attempts up to 5 times using the configurable full reconnect timing values.
     /// Last known pose is preserved during reconnect (m_latestSkeletonStates not cleared).
     /// </summary>
     private System.Collections.IEnumerator ReconnectCoroutine()
@@ -806,13 +883,16 @@ public class OptitrackStreamingClient : MonoBehaviour
         for (int attempt = 1; attempt <= maxAttempts; attempt++)
         {
             m_receivedFrameSinceConnect = false;
-            float delay = (attempt == 1) ? 1.0f : 5.0f;
+            float delay = (attempt == 1)
+                ? Mathf.Max(FullReconnectInitialDelaySeconds, 0f)
+                : Mathf.Max(FullReconnectRetryDelaySeconds, 0.5f);
             Debug.Log(string.Format("{0}: reconnect attempt {1}/{2} in {3} seconds...", GetType().FullName, attempt, maxAttempts, delay), this);
-            yield return new WaitForSeconds(delay);
+            if (delay > 0f)
+                yield return new WaitForSeconds(delay);
 
             yield return StartCoroutine(ConnectCoroutine());
 
-            float deadline = Time.realtimeSinceStartup + 3.0f;
+            float deadline = Time.realtimeSinceStartup + Mathf.Max(FullReconnectFrameWaitSeconds, 0.25f);
             while (!m_receivedFrameSinceConnect && Time.realtimeSinceStartup < deadline)
                 yield return null;
 
@@ -1231,6 +1311,9 @@ public class OptitrackStreamingClient : MonoBehaviour
         {
             OptitrackSkeletonDefinition skelDef = m_skeletonDefinitions[i];
 
+            if (skelDef.IsSynthetic)
+                continue;
+
             if ( skelDef.Name.Equals( skeletonAssetName, StringComparison.InvariantCultureIgnoreCase ) )
             {
                 return skelDef;
@@ -1577,6 +1660,7 @@ public class OptitrackStreamingClient : MonoBehaviour
         }
 
         PruneStatesMissingFromDefinitions();
+        NotifyRegisteredSkeletonDefinitionsChanged();
 
     }
 
@@ -1639,6 +1723,25 @@ public class OptitrackStreamingClient : MonoBehaviour
             SubscribeMarkers();
     }
 
+    private void NotifyRegisteredSkeletonDefinitionsChanged()
+    {
+        if (m_registeredSkeletonComponents.Count == 0)
+            return;
+
+        var registeredSkeletons = new List<MonoBehaviour>(m_registeredSkeletonComponents);
+        foreach (MonoBehaviour component in registeredSkeletons)
+        {
+            if (component == null)
+            {
+                m_registeredSkeletonComponents.Remove(component);
+                continue;
+            }
+
+            if (component is OptitrackSkeletonAnimator_Mingle animator && animator.isActiveAndEnabled)
+                animator.RefreshSkeletonDefinitionBinding();
+        }
+    }
+
     public void RegisterRigidBody( MonoBehaviour component, Int32 rigidBodyId )
     {
         if ( m_rigidBodies.TryGetValue( rigidBodyId, out MonoBehaviour existingComponent ) )
@@ -1673,6 +1776,8 @@ public class OptitrackStreamingClient : MonoBehaviour
 
     public void RegisterSkeleton(MonoBehaviour component, string name)
     {
+        m_registeredSkeletonComponents.Add(component);
+
         if (m_skeletons.TryGetValue(name, out MonoBehaviour existingComponent))
         {
             if (existingComponent == component)
@@ -1899,7 +2004,7 @@ public class OptitrackStreamingClient : MonoBehaviour
         return liveFresh || replayFresh;
     }
 
-    private void StartDirectFrameReceiver(string localAddress, string multicastAddress, UInt16 dataPort)
+    private bool StartDirectFrameReceiver(string localAddress, string multicastAddress, UInt16 dataPort)
     {
         StopDirectFrameReceiver();
 
@@ -1942,11 +2047,13 @@ public class OptitrackStreamingClient : MonoBehaviour
             };
             m_directFrameThread.Start();
             Debug.Log(GetType().FullName + ": direct NatNet frame receiver joined " + multicastAddress + ":" + dataPort + " on " + localAddress + (EnableReplayPriority ? " with replay priority group 239.255.42.100." : "."), this);
+            return true;
         }
         catch (Exception ex)
         {
             StopDirectFrameReceiver();
             Debug.LogWarning(GetType().FullName + ": direct NatNet frame receiver failed to start: " + ex.Message, this);
+            return false;
         }
     }
 
@@ -2095,26 +2202,63 @@ public class OptitrackStreamingClient : MonoBehaviour
         return true;
     }
 
+    private void QueueStreamedTopologyDefinitionRefresh()
+    {
+        if (!AutoRefreshDefinitions || SkipDataDescriptions)
+            return;
+
+        m_pendingDefinitionRefresh = true;
+        m_forceDefinitionRefreshSoon = true;
+    }
+
+    private static bool UpdateFrameTopologyIds(HashSet<Int32> latestIds, HashSet<Int32> currentIds, ref bool hasSnapshot)
+    {
+        if (!hasSnapshot)
+        {
+            latestIds.Clear();
+            foreach (Int32 id in currentIds)
+                latestIds.Add(id);
+            hasSnapshot = true;
+            return false;
+        }
+
+        if (latestIds.SetEquals(currentIds))
+            return false;
+
+        latestIds.Clear();
+        foreach (Int32 id in currentIds)
+            latestIds.Add(id);
+        return true;
+    }
+
     private void ParseDirectRigidBodies(byte[] data, int count, int start, int end, OptitrackHiResTimer.Timestamp frameTimestamp)
     {
         int o = start;
-        for (int i = 0; i < count && o < end; i++)
+        m_currentFrameRigidBodyIds.Clear();
+        for (int i = 0; i < count; i++)
         {
             sRigidBodyData rbData;
             if (!ReadDirectRigidBody(data, ref o, end, out rbData)) return;
+            m_currentFrameRigidBodyIds.Add(rbData.Id);
             OptitrackRigidBodyState rbState = GetOrCreateRigidBodyState(rbData.Id);
             RigidBodyDataToState(rbData, frameTimestamp, rbState);
         }
+
+        if (UpdateFrameTopologyIds(m_latestFrameRigidBodyIds, m_currentFrameRigidBodyIds, ref m_hasFrameRigidBodyTopologySnapshot))
+            QueueStreamedTopologyDefinitionRefresh();
     }
 
     private void ParseDirectSkeletons(byte[] data, int count, int start, int end, OptitrackHiResTimer.Timestamp frameTimestamp)
     {
         int o = start;
-        for (int i = 0; i < count && o + 8 <= end; i++)
+        m_currentFrameSkeletonIds.Clear();
+        for (int i = 0; i < count; i++)
         {
+            if (o + 8 > end) return;
             int skeletonId = BitConverter.ToInt32(data, o); o += 4;
             int boneCount = BitConverter.ToInt32(data, o); o += 4;
             if (boneCount < 0 || boneCount > 4096 || o + boneCount * 38 > end) return;
+            m_currentFrameSkeletonIds.Add(skeletonId);
 
             sRigidBodyData[] stagedBones = GetSkeletonFrameScratch(skeletonId, boneCount);
             for (int b = 0; b < boneCount; b++)
@@ -2124,6 +2268,9 @@ public class OptitrackStreamingClient : MonoBehaviour
 
             CommitDirectSkeletonFrame(skeletonId, stagedBones, boneCount, frameTimestamp);
         }
+
+        if (UpdateFrameTopologyIds(m_latestFrameSkeletonIds, m_currentFrameSkeletonIds, ref m_hasFrameSkeletonTopologySnapshot))
+            QueueStreamedTopologyDefinitionRefresh();
     }
 
     private void CommitDirectSkeletonFrame(int skeletonId, sRigidBodyData[] stagedBones, int boneCount, OptitrackHiResTimer.Timestamp frameTimestamp)
@@ -2136,8 +2283,7 @@ public class OptitrackStreamingClient : MonoBehaviour
 
         if (skelDef == null)
         {
-            if (!m_pendingDefinitionRefresh)
-                m_pendingDefinitionRefresh = true;
+            QueueStreamedTopologyDefinitionRefresh();
             return;
         }
 
@@ -2208,6 +2354,7 @@ public class OptitrackStreamingClient : MonoBehaviour
         {
             Id = skeletonId,
             Name = skeletonName,
+            IsSynthetic = true,
             Bones = new List<OptitrackSkeletonDefinition.BoneDefinition>(boneCount),
             BoneIdToParentIdMap = new Dictionary<int, int>(),
         };
@@ -2237,6 +2384,7 @@ public class OptitrackStreamingClient : MonoBehaviour
 
         m_skeletonDefinitions.Add(skelDef);
         m_mirrorBoneIdMaps.Clear();
+        m_pendingSkeletonDefinitionNotify = true;
         return skelDef;
     }
 
@@ -2415,12 +2563,94 @@ public class OptitrackStreamingClient : MonoBehaviour
 
         ServerNatNetVersion = natNetVersion[0] + "." + natNetVersion[1] + "." + natNetVersion[2] + "." + natNetVersion[3];
         ClientNatNetVersion = "Direct UDP";
-        m_directNatNetConnected = true;
-        StartDirectFrameReceiver(localAddr.ToString(), negotiatedMulticast.ToString(), negotiatedDataPort);
+        if (!StartDirectFrameReceiver(localAddr.ToString(), negotiatedMulticast.ToString(), negotiatedDataPort))
+            return false;
+        StoreDirectEndpoint(serverAddr, localAddr, commandPort, negotiatedDataPort, negotiatedMulticast);
+        m_nextAutoDefinitionRefreshTime = Time.unscaledTime + Mathf.Max(DefinitionRefreshInterval, 1f);
         Debug.Log(GetType().FullName + ": Connected to direct NatNet server. Server=" + serverAddr + ", host=" + hostName + ", local=" + localAddr + ", serverNatNet=" + ServerNatNetVersion + ", multicast=" + negotiatedMulticast + ":" + negotiatedDataPort + ".", this);
         return true;
     }
 
+    private void StoreDirectEndpoint(IPAddress serverAddr, IPAddress localAddr, UInt16 commandPort, UInt16 dataPort, IPAddress multicastAddr)
+    {
+        m_directServerAddress = serverAddr;
+        m_directLocalAddress = localAddr;
+        m_directCommandPort = commandPort;
+        m_directDataPort = dataPort;
+        m_directMulticastAddress = multicastAddr;
+    }
+
+    private void UpdateDirectDefinitions()
+    {
+        IPAddress serverAddr;
+        IPAddress localAddr;
+        IPAddress multicastAddr = null;
+        UInt16 commandPort;
+        UInt16 dataPort;
+
+        try
+        {
+            serverAddr = IPAddress.Parse(ServerAddress);
+            commandPort = (UInt16)Mathf.Clamp(CommandPort, 1, 65535);
+            dataPort = (UInt16)Mathf.Clamp(DataPort, 1, 65535);
+            if (!string.IsNullOrWhiteSpace(MulticastAddress))
+                multicastAddr = IPAddress.Parse(MulticastAddress.Trim());
+            localAddr = ResolveLocalAddress(serverAddr);
+            ResolvedLocalAddress = localAddr.ToString();
+        }
+        catch (Exception ex)
+        {
+            throw new InvalidOperationException("Error parsing direct NatNet refresh settings.", ex);
+        }
+
+        string hostName;
+        byte[] appVersion;
+        byte[] natNetVersion;
+        byte[] modelDefPacket;
+        UInt16 negotiatedDataPort = dataPort;
+        IPAddress negotiatedMulticast = multicastAddr ?? IPAddress.Parse("239.255.42.99");
+
+        if (DirectRequestServerInfo(serverAddr, localAddr, commandPort, out hostName, out appVersion, out natNetVersion, out negotiatedDataPort, out negotiatedMulticast))
+        {
+            if (negotiatedDataPort == 0)
+                negotiatedDataPort = dataPort;
+            if (negotiatedMulticast == null)
+                negotiatedMulticast = multicastAddr ?? IPAddress.Parse("239.255.42.99");
+
+            ServerNatNetVersion = natNetVersion[0] + "." + natNetVersion[1] + "." + natNetVersion[2] + "." + natNetVersion[3];
+        }
+        else
+        {
+            negotiatedDataPort = dataPort;
+            negotiatedMulticast = multicastAddr ?? IPAddress.Parse("239.255.42.99");
+        }
+
+        if (!DirectRequestModelDef(serverAddr, localAddr, commandPort, out modelDefPacket))
+            throw new InvalidOperationException("Direct NatNet MODELDEF request failed.");
+        if (!DirectUpdateDefinitions(modelDefPacket))
+            throw new InvalidOperationException("Direct NatNet MODELDEF parse failed.");
+
+        bool dataEndpointChanged =
+            m_directServerAddress == null ||
+            m_directLocalAddress == null ||
+            m_directMulticastAddress == null ||
+            !m_directServerAddress.Equals(serverAddr) ||
+            !m_directLocalAddress.Equals(localAddr) ||
+            !m_directMulticastAddress.Equals(negotiatedMulticast) ||
+            m_directCommandPort != commandPort ||
+            m_directDataPort != negotiatedDataPort;
+
+        if (dataEndpointChanged)
+        {
+            if (!StartDirectFrameReceiver(localAddr.ToString(), negotiatedMulticast.ToString(), negotiatedDataPort))
+                throw new InvalidOperationException("Direct NatNet frame receiver failed to restart after endpoint change.");
+            Debug.Log(GetType().FullName + ": direct NatNet frame endpoint changed during refresh; receiver restarted on " + negotiatedMulticast + ":" + negotiatedDataPort + ".", this);
+        }
+
+        StoreDirectEndpoint(serverAddr, localAddr, commandPort, negotiatedDataPort, negotiatedMulticast);
+        ClientNatNetVersion = "Direct UDP";
+    }
+
     private bool DirectRequestServerInfo(IPAddress serverAddr, IPAddress localAddr, UInt16 commandPort, out string hostName, out byte[] appVersion, out byte[] natNetVersion, out UInt16 dataPort, out IPAddress multicastAddress)
     {
         hostName = "";
@@ -2431,7 +2661,7 @@ public class OptitrackStreamingClient : MonoBehaviour
 
         byte[] response;
         byte[] pingPayload = DirectBuildPingPayload();
-        if (!DirectCommandRequest(serverAddr, localAddr, commandPort, 0, pingPayload, 2000, out response)) // NAT_PING
+        if (!DirectCommandRequest(serverAddr, localAddr, commandPort, 0, pingPayload, Mathf.Max(DirectServerInfoTimeoutMs, 100), out response)) // NAT_PING
             return false;
         if (response.Length < 4 || BitConverter.ToUInt16(response, 0) != 1) // NAT_PINGRESPONSE / server info
             return false;
@@ -2469,7 +2699,7 @@ public class OptitrackStreamingClient : MonoBehaviour
     {
         modelDefPacket = null;
         byte[] response;
-        if (!DirectCommandRequest(serverAddr, localAddr, commandPort, 4, null, 3000, out response)) // NAT_REQUEST_MODELDEF
+        if (!DirectCommandRequest(serverAddr, localAddr, commandPort, 4, null, Mathf.Max(DirectModelDefTimeoutMs, 100), out response)) // NAT_REQUEST_MODELDEF
             return false;
         if (response.Length < 8 || BitConverter.ToUInt16(response, 0) != 5) // NAT_MODELDEF
             return false;
@@ -2583,6 +2813,7 @@ public class OptitrackStreamingClient : MonoBehaviour
         }
 
         PruneStatesMissingFromDefinitions();
+        NotifyRegisteredSkeletonDefinitionsChanged();
 
         return true;
     }
@@ -2880,12 +3111,12 @@ public class OptitrackStreamingClient : MonoBehaviour
 
     System.Collections.IEnumerator CheckConnectionHealth()
     {
-        const float kHealthCheckIntervalSeconds = 1.0f;
-        const float kRecentFrameThresholdSeconds = 5.0f;
+        float healthCheckIntervalSeconds = Mathf.Max(ConnectionHealthCheckIntervalSeconds, 0.1f);
+        float recentFrameThresholdSeconds = Mathf.Max(StreamingFrameTimeoutSeconds, healthCheckIntervalSeconds);
 
         // The lifespan of these variables is tied to the lifespan of a single connection session.
         // The coroutine is stopped on disconnect and restarted on connect.
-        YieldInstruction checkIntervalYield = new WaitForSeconds( kHealthCheckIntervalSeconds );
+        YieldInstruction checkIntervalYield = new WaitForSeconds( healthCheckIntervalSeconds );
         OptitrackHiResTimer.Timestamp connectionInitiatedTimestamp = OptitrackHiResTimer.Now();
         bool wasReceivingFrames = false;
         bool warnedPendingFirstFrame = false;
@@ -2897,7 +3128,7 @@ public class OptitrackStreamingClient : MonoBehaviour
             if ( m_receivedFrameSinceConnect == false && !IsReplayFrameFresh() )
             {
                 // Still waiting for first frame. Warn exactly once if this takes too long.
-                if ( connectionInitiatedTimestamp.AgeSeconds > kRecentFrameThresholdSeconds )
+                if ( connectionInitiatedTimestamp.AgeSeconds > recentFrameThresholdSeconds )
                 {
                     if ( warnedPendingFirstFrame == false )
                     {
@@ -2906,6 +3137,12 @@ public class OptitrackStreamingClient : MonoBehaviour
                         else
                             Debug.LogWarning( GetType().FullName + ": No frames received from the server yet. Verify your connection settings are correct and that the server is streaming.", this );
                         warnedPendingFirstFrame = true;
+
+                        if ( AutoReconnect )
+                        {
+                            Debug.Log( GetType().FullName + ": starting automatic reconnect while waiting for the first streaming frame.", this );
+                            Reconnect();
+                        }
                     }
 
                     continue;
@@ -2914,7 +3151,7 @@ public class OptitrackStreamingClient : MonoBehaviour
             else
             {
                 // We've received at least one frame, do ongoing checks for changes in connection health.
-                bool receivedRecentFrame = HasRecentStreamingFrame(kRecentFrameThresholdSeconds);
+                bool receivedRecentFrame = HasRecentStreamingFrame(recentFrameThresholdSeconds);
 
                 if ( wasReceivingFrames == false && receivedRecentFrame == true )
                 {
@@ -2928,11 +3165,6 @@ public class OptitrackStreamingClient : MonoBehaviour
                     // Transition: Good health -> bad health.
                     wasReceivingFrames = false;
                     Debug.LogWarning( GetType().FullName + ": No streaming frames received from the server recently.", this );
-                    if (m_directNatNetConnected)
-                    {
-                        Debug.LogWarning(GetType().FullName + ": direct UDP receiver stays active; automatic reconnect is skipped to avoid interrupting live/replay multicast.", this);
-                        continue;
-                    }
                     if ( AutoReconnect )
                     {
                         Debug.Log( GetType().FullName + ": starting automatic reconnect.", this );
@@ -3005,16 +3237,21 @@ public class OptitrackStreamingClient : MonoBehaviour
             result = NaturalPoint.NatNetLib.NativeMethods.NatNet_Frame_GetRigidBodyCount( pFrame, out frameRbCount );
             NatNetException.ThrowIfNotOK( result, "NatNet_Frame_GetRigidBodyCount failed." );
 
+            m_currentFrameRigidBodyIds.Clear();
             for (int rbIdx = 0; rbIdx < frameRbCount; ++rbIdx)
             {
                 sRigidBodyData rbData = new sRigidBodyData();
                 result = NaturalPoint.NatNetLib.NativeMethods.NatNet_Frame_GetRigidBody( pFrame, rbIdx, out rbData );
                 NatNetException.ThrowIfNotOK( result, "NatNet_Frame_GetRigidBody failed." );
 
+                m_currentFrameRigidBodyIds.Add(rbData.Id);
+
                 // Ensure we have a state corresponding to this rigid body ID.
                 OptitrackRigidBodyState rbState = GetOrCreateRigidBodyState( rbData.Id );
                 RigidBodyDataToState(rbData, OptitrackHiResTimer.Now(), rbState);
             }
+            if (UpdateFrameTopologyIds(m_latestFrameRigidBodyIds, m_currentFrameRigidBodyIds, ref m_hasFrameRigidBodyTopologySnapshot))
+                QueueStreamedTopologyDefinitionRefresh();
 
             // ----------------------
             // - Update skeletons
@@ -3023,12 +3260,15 @@ public class OptitrackStreamingClient : MonoBehaviour
             result = NaturalPoint.NatNetLib.NativeMethods.NatNet_Frame_GetSkeletonCount( pFrame, out frameSkeletonCount );
             NatNetException.ThrowIfNotOK( result, "NatNet_Frame_GetSkeletonCount failed." );
 
+            m_currentFrameSkeletonIds.Clear();
             for (int skelIdx = 0; skelIdx < frameSkeletonCount; ++skelIdx)
             {
                 Int32 skeletonId;
                 result = NaturalPoint.NatNetLib.NativeMethods.NatNet_Frame_Skeleton_GetId( pFrame, skelIdx, out skeletonId );
                 NatNetException.ThrowIfNotOK( result, "NatNet_Frame_Skeleton_GetId failed." );
 
+                m_currentFrameSkeletonIds.Add(skeletonId);
+
                 // Ensure we have a state corresponding to this skeleton ID.
                 OptitrackSkeletonState skelState = GetOrCreateSkeletonState( skeletonId );
 
@@ -3043,8 +3283,8 @@ public class OptitrackStreamingClient : MonoBehaviour
                     if (!m_pendingDefinitionRefresh)
                     {
                         Debug.LogWarning(GetType().FullName + ": missing skeleton definition for streamed skeleton ID " + skeletonId + "; scheduling definition refresh.", this);
-                        m_pendingDefinitionRefresh = true;
                     }
+                    QueueStreamedTopologyDefinitionRefresh();
                     continue;
                 }
 
@@ -3103,6 +3343,8 @@ public class OptitrackStreamingClient : MonoBehaviour
 
                 skelState.DeliveryTimestamp = frameTimestamp;
             }
+            if (UpdateFrameTopologyIds(m_latestFrameSkeletonIds, m_currentFrameSkeletonIds, ref m_hasFrameSkeletonTopologySnapshot))
+                QueueStreamedTopologyDefinitionRefresh();
 
             // -----------------------------------------------------
             // - Update trained markerset // trained markerset added