diff --git a/src/network/network_server.cpp b/src/network/network_server.cpp
--- a/src/network/network_server.cpp
+++ b/src/network/network_server.cpp
@@ -305,7 +305,7 @@ NetworkRecvStatus ServerNetworkGameSocke
 /* static */ bool ServerNetworkGameSocketHandler::AllowConnection()
 {
 	extern byte _network_clients_connected;
-	bool accept = _network_clients_connected < MAX_CLIENTS && _network_game_info.clients_on < _settings_client.network.max_clients;
+	bool accept = _network_clients_connected < MAX_CLIENTS;
 
 	/* We can't go over the MAX_CLIENTS limit here. However, the
 	 * pool must have place for all clients and ourself. */
@@ -805,6 +805,11 @@ NetworkRecvStatus ServerNetworkGameSocke
 		return this->SendError(NETWORK_ERROR_NOT_EXPECTED);
 	}
 
+	if (_network_game_info.clients_on >= _settings_client.network.max_clients) {
+		/* Turns out we are full. Inform the user about this. */
+		return this->SendError(NETWORK_ERROR_FULL);
+	}
+
 	std::string client_revision = p->Recv_string(NETWORK_REVISION_LENGTH);
 	uint32 newgrf_version = p->Recv_uint32();