diff --git a/server/gns_gameplay_adapter.py b/server/gns_gameplay_adapter.py
index ed9fd62..db2eeca 100644
--- a/server/gns_gameplay_adapter.py
+++ b/server/gns_gameplay_adapter.py
@@ -1,13 +1,12 @@
 from __future__ import annotations
 
-import json
 import threading
 import time
 from dataclasses import dataclass
 from typing import TYPE_CHECKING
 
 from client_session import ClientSession
-from gns_transport import EventType, GnsEvent, GnsServerTransport, RemoteEndpoint, SendResult
+from gns_transport import EventType, GnsEvent, GnsServerTransport, GnsTransportError, SendResult
 from packet_codec import EncodedPacket, PacketCodecError, decode_packet
 from transport_policy import delivery_for_packet_type, is_snapshot_packet
 
@@ -51,8 +50,12 @@ class GnsConnectionAdapter:
         packet_type = packet["type"]
         encoded = EncodedPacket(packet_type, payload, delivery_for_packet_type(packet_type))
         result = self.transport.send_encoded(self.connection_id, encoded)
-        if result in (SendResult.SENT, SendResult.DROPPED):
+        if result is SendResult.SENT:
             return
+        if result is SendResult.DROPPED and is_snapshot_packet(packet_type):
+            return
+        if result is SendResult.DROPPED:
+            raise OSError("GNS refused to queue a reliable message")
         if result is SendResult.BACKPRESSURE and is_snapshot_packet(packet_type):
             return
         if result is SendResult.BACKPRESSURE:
@@ -94,13 +97,15 @@ class GnsGameplayAdapter:
         self.transport.send_packet(connection_id, packet)
 
     def _welcome_packet(self, client: ClientSession) -> dict:
+        from server_core import PROTOCOL_VERSION
+
         return {
             "type": "welcome",
             "playerId": client.player_id,
             "serverTime": time.time(),
             "serverName": self.server.server_name,
             "serverDescription": self.server.server_description,
-            "protocolVersion": self.server.PROTOCOL_VERSION if hasattr(self.server, "PROTOCOL_VERSION") else 2,
+            "protocolVersion": PROTOCOL_VERSION,
             "capabilities": [
                 "interest-v1",
                 "hello-v2",
@@ -270,7 +275,13 @@ class GnsGameplayAdapter:
             with self._lock:
                 if not self._thread_running:
                     break
-            processed = self.pump_once()
+            try:
+                processed = self.pump_once()
+            except GnsTransportError as error:
+                self.server._log(f"GNS transport loop stopped: {error}", level="error")
+                with self._lock:
+                    self._thread_running = False
+                break
             if processed == 0:
                 time.sleep(0.002)
 
@@ -293,7 +304,10 @@ class GnsGameplayAdapter:
         for connection_id, client in clients:
             if isinstance(client.connection, GnsConnectionAdapter):
                 client.connection.mark_remote_closed()
-            self.transport.disconnect(connection_id, debug="GNS adapter stopped")
+            try:
+                self.transport.disconnect(connection_id, debug="GNS adapter stopped")
+            except Exception:
+                pass
             self.server._disconnect_client(client)
         with self._lock:
             self._clients.clear()