fix: NetworkTransport early and post late updates

com.unity.netcode.gameobjects/Runtime/Core/NetworkManager.cs

@@ -9,6 +9,7 @@
 #endif
 using UnityEngine.SceneManagement;
 using Debug = UnityEngine.Debug;
+using Unity.Netcode.Transports.UTP;
 
 namespace Unity.Netcode
 {
@@ -291,6 +292,10 @@ public void NetworkUpdate(NetworkUpdateStage updateStage)
                 case NetworkUpdateStage.EarlyUpdate:
                     {
                         UpdateTopology();
+
+                        // Handle processing any new connections or transport events
+                        NetworkConfig.NetworkTransport.EarlyUpdate();
+
                         ConnectionManager.ProcessPendingApprovals();
                         ConnectionManager.PollAndHandleNetworkEvents();
 
@@ -379,6 +384,9 @@ public void NetworkUpdate(NetworkUpdateStage updateStage)
                         // Metrics update needs to be driven by NetworkConnectionManager's update to assure metrics are dispatched after the send queue is processed.
                         MetricsManager.UpdateMetrics();
 
+                        // Handle sending any pending transport messages 
+                        NetworkConfig.NetworkTransport.PostLateUpdate();
+
                         // TODO: Determine a better way to handle this
                         NetworkObject.VerifyParentingStatus();
 

com.unity.netcode.gameobjects/Runtime/Transports/NetworkTransport.cs

@@ -107,6 +107,22 @@ protected void InvokeOnTransportEvent(NetworkEvent eventType, ulong clientId, Ar
         /// /// <param name="networkManager">optionally pass in NetworkManager</param>
         public abstract void Initialize(NetworkManager networkManager = null);
 
+        /// <summary>
+        /// Invoked by NetworkManager at the beginning of its EarlyUpdate
+        /// </summary>
+        internal virtual void EarlyUpdate()
+        {
+
+        }
+
+        /// <summary>
+        /// Invoked by NetworkManager during PostLateUpdate
+        /// </summary>
+        internal virtual void PostLateUpdate()
+        {
+
+        }
+
         protected virtual NetworkTopologyTypes OnCurrentTopology()
         {
             return NetworkTopologyTypes.ClientServer;

com.unity.netcode.gameobjects/Runtime/Transports/UTP/UnityTransport.cs

@@ -944,17 +944,13 @@ private bool ProcessEvent()
             return false;
         }
 
-        private void Update()
+        private JobHandle m_FlushSendJobHandle;
+
+        internal override void EarlyUpdate()
         {
+            m_FlushSendJobHandle.Complete();
             if (m_Driver.IsCreated)
             {
-                foreach (var kvp in m_SendQueue)
-                {
-                    SendBatchedMessages(kvp.Key, kvp.Value);
-                }
-
-                m_Driver.ScheduleUpdate().Complete();
-
                 if (m_ProtocolType == ProtocolType.RelayUnityTransport && m_Driver.GetRelayConnectionStatus() == RelayConnectionStatus.AllocationInvalid)
                 {
                     Debug.LogError("Transport failure! Relay allocation needs to be recreated, and NetworkManager restarted. " +
@@ -964,6 +960,8 @@ private void Update()
                     return;
                 }
 
+                m_Driver.ScheduleUpdate().Complete();
+
                 while (AcceptConnection() && m_Driver.IsCreated)
                 {
                     ;
@@ -973,14 +971,35 @@ private void Update()
                 {
                     ;
                 }
+            }
+        }
 
-#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
-                if (m_NetworkManager)
+        internal override void PostLateUpdate()
+        {
+            if (m_Driver.IsCreated)
+            {
+                foreach (var kvp in m_SendQueue)
                 {
-                    ExtractNetworkMetrics();
+                    SendBatchedMessages(kvp.Key, kvp.Value);
                 }
-#endif
+
+                // Schedule a flush send as the last transport action for the
+                // current frame.
+                m_FlushSendJobHandle = m_Driver.ScheduleFlushSend(default);
+            }
+
+#if MULTIPLAYER_TOOLS_1_0_0_PRE_7
+            if (m_NetworkManager)
+            {
+                ExtractNetworkMetrics();
             }
+#endif
+            base.PostLateUpdate();
+        }
+
+        private void Update()
+        {
+
         }
 
         private void OnDestroy()