elif isinstance(error, ConnectionFailure):
            # "Client MUST replace the server's description with type Unknown
            # ... MUST NOT request an immediate check of the server."
            if not self._settings.load_balanced:
                await self._process_change(ServerDescription(address, error=error))
            # Clear the pool.
            await server.reset(service_id)
            # "When a client marks a server Unknown from `Network error when
            # reading or writing`_, clients MUST cancel the hello check on
            # that server and close the current monitoring connection."
            server._monitor.cancel_check()