diff --git a/server/src/Vanguard.Server/Matches/MatchGrain.cs b/server/src/Vanguard.Server/Matches/MatchGrain.cs
index 0eac1eb..ed7bff5 100644
--- a/server/src/Vanguard.Server/Matches/MatchGrain.cs
+++ b/server/src/Vanguard.Server/Matches/MatchGrain.cs
@@ -201,7 +201,19 @@ public sealed class MatchGrain : IMatchGrain
         IMatchConnection connection,
         long resumeFromSeq)
     {
-        _connections.Register(_matchId, seat, connection);
+        var previous = _connections.Register(_matchId, seat, connection);
+        if (previous is not null && !ReferenceEquals(previous, connection))
+        {
+            try
+            {
+                await previous.CloseAsync(4409, "replaced");
+            }
+            catch (Exception exception)
+            {
+                _logger.LogDebug(exception, "Match {MatchId}: closing old connection failed.", _matchId);
+            }
+        }
+
         var attached = await AttachAsync(seat, playerId, resumeFromSeq);
 
         if (!attached)
diff --git a/server/tests/Vanguard.Server.Tests/OrleansMatchTests.cs b/server/tests/Vanguard.Server.Tests/OrleansMatchTests.cs
index 5e94cf0..b8c0184 100644
--- a/server/tests/Vanguard.Server.Tests/OrleansMatchTests.cs
+++ b/server/tests/Vanguard.Server.Tests/OrleansMatchTests.cs
@@ -95,6 +95,13 @@ public class OrleansMatchTests
 
         public void Configure(ISiloBuilder siloBuilder)
         {
+            siloBuilder.ConfigureLogging(logging =>
+            {
+                logging.ClearProviders();
+                logging.AddConsole();
+                logging.SetMinimumLevel(LogLevel.Debug);
+            });
+
             siloBuilder.ConfigureServices(services =>
             {
                 var options = ServerTestData.SmallOptions();