diff --git a/gns3server/utils/asyncio/telnet_server.py b/gns3server/utils/asyncio/telnet_server.py
index 8f571d1f1..a6b54d706 100644
--- a/gns3server/utils/asyncio/telnet_server.py
+++ b/gns3server/utils/asyncio/telnet_server.py
@@ -251,8 +251,12 @@ class AsyncioTelnetServer:
     async def _invoke_window_size_changed(self, connection, columns, rows):
         try:
             await connection.window_size_changed(columns, rows)
+        except asyncio.CancelledError:
+            raise
         except (ConnectionError, OSError):
             connection.close()
+        except Exception:
+            log.exception("Unhandled exception in window_size_changed callback for %r", connection)
 
     async def _run_client_session(self, network_reader, network_writer):
         self._set_socket_options(network_writer)
diff --git a/tests/utils/asyncio/test_telnet_server.py b/tests/utils/asyncio/test_telnet_server.py
index dcd1c1efe..d91fb91c9 100644
--- a/tests/utils/asyncio/test_telnet_server.py
+++ b/tests/utils/asyncio/test_telnet_server.py
@@ -143,7 +143,7 @@ async def test_telnet_server_broadcast_survives_client_disconnect():
         await _wait_for_connection_count(server, 2)
 
         client1_writer.close()
-        await asyncio.sleep(0.2)
+        await _wait_for_connection_count(server, 1)
 
         upstream_reader.feed_data(b"ok")
         data2 = await asyncio.wait_for(client2_reader.read(2), timeout=2)