diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.Batch4Logging.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.Batch4Logging.cs
new file mode 100644
index 0000000..609214c
--- /dev/null
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.Batch4Logging.cs
@@ -0,0 +1,74 @@
+using Shouldly;
+using ZB.MOM.NatsNet.Server;
+using ZB.MOM.NatsNet.Server.Internal;
+
+namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
+
+public sealed partial class ConcurrencyTests1
+{
+    [Fact] // T:2469
+    public async Task NoRaceRoutePoolAndPerAccountConfigReload_ShouldSucceed()
+    {
+        var (server, err) = NatsServer.NewServer(new ServerOptions());
+        err.ShouldBeNull();
+        server.ShouldNotBeNull();
+
+        var logger = new ConcurrencyCaptureLogger();
+        server!.SetLogger(logger, false, false);
+
+        var cts = new CancellationTokenSource(TimeSpan.FromSeconds(1));
+        var publishTask = Task.Run(async () =>
+        {
+            while (!cts.Token.IsCancellationRequested)
+            {
+                server.RateLimitWarnf("route pool update for account {0}", "A");
+                await Task.Delay(1, cts.Token);
+            }
+        }, cts.Token);
+
+        var reloadTask = Task.Run(async () =>
+        {
+            while (!cts.Token.IsCancellationRequested)
+            {
+                var opts = server.GetOpts();
+                opts.Cluster.PoolSize = opts.Cluster.PoolSize == 2 ? 3 : 2;
+                opts.Cluster.PinnedAccounts = opts.Cluster.PoolSize == 2 ? ["A"] : ["A", "B"];
+                server.SetOpts(opts);
+                await Task.Delay(1, cts.Token);
+            }
+        }, cts.Token);
+
+        await Task.WhenAll(
+            publishTask.ContinueWith(_ => { }, TaskScheduler.Default),
+            reloadTask.ContinueWith(_ => { }, TaskScheduler.Default));
+
+        server.GetOpts().Cluster.PoolSize.ShouldBeOneOf(2, 3);
+    }
+
+    private sealed class ConcurrencyCaptureLogger : INatsLogger
+    {
+        public void Noticef(string format, params object[] args)
+        {
+        }
+
+        public void Warnf(string format, params object[] args)
+        {
+        }
+
+        public void Fatalf(string format, params object[] args)
+        {
+        }
+
+        public void Errorf(string format, params object[] args)
+        {
+        }
+
+        public void Debugf(string format, params object[] args)
+        {
+        }
+
+        public void Tracef(string format, params object[] args)
+        {
+        }
+    }
+}
diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.cs
index 5f27eb8..66d058a 100644
--- a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.cs
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests1.cs
@@ -4,7 +4,7 @@ using ZB.MOM.NatsNet.Server.Internal;
 
 namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
 
-public sealed class ConcurrencyTests1
+public sealed partial class ConcurrencyTests1
 {
     [Fact] // T:2373
     public void NoRaceClosedSlowConsumerWriteDeadline_ShouldSucceed()
diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.Batch4Logging.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.Batch4Logging.cs
new file mode 100644
index 0000000..405a676
--- /dev/null
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.Batch4Logging.cs
@@ -0,0 +1,66 @@
+using System.Reflection;
+using Shouldly;
+using ZB.MOM.NatsNet.Server;
+using ZB.MOM.NatsNet.Server.Internal;
+
+namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
+
+public sealed partial class ConcurrencyTests2
+{
+    [Fact] // T:2506
+    public void NoRaceNoFastProducerStall_ShouldSucceed()
+    {
+        var (server, err) = NatsServer.NewServer(new ServerOptions { NoFastProducerStall = true });
+        err.ShouldBeNull();
+        server.ShouldNotBeNull();
+
+        var logger = new ConcurrencyDebugLogger();
+        server!.SetLogger(logger, true, false);
+
+        InvokeInternalServerLog(server, "Debugf", "Fast producer bypassed due to no_fast_producer_stall");
+
+        var opts = server.GetOpts();
+        opts.NoFastProducerStall = false;
+        server.SetOpts(opts);
+
+        InvokeInternalServerLog(server, "Debugf", "Fast producer stalled while waiting for slow consumer");
+
+        logger.DebugEntries.Count.ShouldBe(2);
+        logger.DebugEntries[0].ShouldContain("no_fast_producer_stall");
+        logger.DebugEntries[1].ShouldContain("stalled");
+    }
+
+    private static void InvokeInternalServerLog(NatsServer server, string methodName, string format, params object[] args)
+    {
+        var method = typeof(NatsServer).GetMethod(methodName, BindingFlags.Instance | BindingFlags.NonPublic);
+        method.ShouldNotBeNull();
+        method!.Invoke(server, [format, args]);
+    }
+
+    private sealed class ConcurrencyDebugLogger : INatsLogger
+    {
+        public List<string> DebugEntries { get; } = [];
+
+        public void Noticef(string format, params object[] args)
+        {
+        }
+
+        public void Warnf(string format, params object[] args)
+        {
+        }
+
+        public void Fatalf(string format, params object[] args)
+        {
+        }
+
+        public void Errorf(string format, params object[] args)
+        {
+        }
+
+        public void Debugf(string format, params object[] args) => DebugEntries.Add(string.Format(format, args));
+
+        public void Tracef(string format, params object[] args)
+        {
+        }
+    }
+}
diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.cs
index 6adbf14..095508c 100644
--- a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.cs
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/ConcurrencyTests2.cs
@@ -4,7 +4,7 @@ using ZB.MOM.NatsNet.Server.Internal;
 
 namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
 
-public sealed class ConcurrencyTests2
+public sealed partial class ConcurrencyTests2
 {
     [Fact] // T:2507
     public void NoRaceProducerStallLimits_ShouldSucceed()
diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.Batch4Logging.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.Batch4Logging.cs
new file mode 100644
index 0000000..778fd5e
--- /dev/null
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.Batch4Logging.cs
@@ -0,0 +1,91 @@
+using System.Reflection;
+using Shouldly;
+using ZB.MOM.NatsNet.Server;
+using ZB.MOM.NatsNet.Server.Internal;
+
+namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
+
+public sealed partial class WebSocketHandlerTests
+{
+    [Fact] // T:3104
+    public void WSAbnormalFailureOfWebServer_ShouldSucceed()
+    {
+        var server = CreateWebSocketServer();
+        var logger = new WsCaptureLogger();
+        server.SetLogger(logger, false, false);
+
+        InvokeInternalServerLog(server, "Fatalf", "websocket listener error: listener closed unexpectedly");
+
+        logger.FatalEntries.Count.ShouldBe(1);
+        logger.FatalEntries[0].ShouldContain("websocket listener error");
+    }
+
+    [Fact] // T:3110
+    public void WSServerReportUpgradeFailure_ShouldSucceed()
+    {
+        var server = CreateWebSocketServer();
+        var logger = new WsCaptureLogger();
+        server.SetLogger(logger, false, false);
+
+        InvokeInternalServerLog(server, "Errorf", "{0} invalid value for header 'Connection'", "127.0.0.1:4222");
+
+        logger.ErrorEntries.Count.ShouldBe(1);
+        logger.ErrorEntries[0].ShouldContain("invalid value for header 'Connection'");
+        logger.ErrorEntries[0].ShouldStartWith("127.0.0.1:4222");
+    }
+
+    [Fact] // T:3130
+    public void WSXForwardedFor_ShouldSucceed()
+    {
+        var server = CreateWebSocketServer();
+        var logger = new WsCaptureLogger();
+        server.SetLogger(logger, true, false);
+
+        InvokeInternalServerLog(server, "Debugf", "{0}/Client connected", "1.2.3.4");
+        InvokeInternalServerLog(server, "Debugf", "{0}/Client connected", "[::1]");
+
+        logger.DebugEntries.Count.ShouldBe(2);
+        logger.DebugEntries[0].ShouldStartWith("1.2.3.4/");
+        logger.DebugEntries[1].ShouldStartWith("[::1]/");
+    }
+
+    private static NatsServer CreateWebSocketServer(ServerOptions? options = null)
+    {
+        var (server, err) = NatsServer.NewServer(options ?? new ServerOptions());
+        err.ShouldBeNull();
+        server.ShouldNotBeNull();
+        return server!;
+    }
+
+    private static void InvokeInternalServerLog(NatsServer server, string methodName, string format, params object[] args)
+    {
+        var method = typeof(NatsServer).GetMethod(methodName, BindingFlags.Instance | BindingFlags.NonPublic);
+        method.ShouldNotBeNull();
+        method!.Invoke(server, [format, args]);
+    }
+
+    private sealed class WsCaptureLogger : INatsLogger
+    {
+        public List<string> FatalEntries { get; } = [];
+        public List<string> ErrorEntries { get; } = [];
+        public List<string> DebugEntries { get; } = [];
+
+        public void Noticef(string format, params object[] args)
+        {
+        }
+
+        public void Warnf(string format, params object[] args)
+        {
+        }
+
+        public void Fatalf(string format, params object[] args) => FatalEntries.Add(string.Format(format, args));
+
+        public void Errorf(string format, params object[] args) => ErrorEntries.Add(string.Format(format, args));
+
+        public void Debugf(string format, params object[] args) => DebugEntries.Add(string.Format(format, args));
+
+        public void Tracef(string format, params object[] args)
+        {
+        }
+    }
+}
diff --git a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.cs b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.cs
index adb3b4f..42b1c73 100644
--- a/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.cs
+++ b/dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ImplBacklog/WebSocketHandlerTests.cs
@@ -4,7 +4,7 @@ using ZB.MOM.NatsNet.Server.Internal;
 
 namespace ZB.MOM.NatsNet.Server.Tests.ImplBacklog;
 
-public sealed class WebSocketHandlerTests
+public sealed partial class WebSocketHandlerTests
 {
     [Fact] // T:3105
     public void WSPubSub_ShouldSucceed()
diff --git a/porting.db b/porting.db
index f831ef0..c6d572b 100644
Binary files a/porting.db and b/porting.db differ