Default ENetMultiplayerPeer disconnecting on LAN

[janavarro95]

Tested versions

-Reproducible in Godot 4.3, 4.4.1.stable, 4.5.dev2

System information

Godot v4.4.1.stable - Windows 10 (build 19045) - Multi-window, 1 monitor - OpenGL 3 (Compatibility) - NVIDIA GeForce GTX 1660 SUPER (NVIDIA; 32.0.15.6590) - Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz (20 threads)

Issue description

When creating a server and client for a multiplayer game, I noticed that when I have the client and server running on two separate computers on the same network (LAN) that after a random amount of seconds the client will disconnect from the server without an error on either the client or server. The only information I have to go off of is the method I connected to multiplayer.peer_disconnected which only tells me the peers id. I do not expect this disconnect to happen as neither a crash happens, an error by Godot is never displayed to the editor, nor is multiplayer.multiplayer_peer.disconnect_peer(id) ever called. The ENetMultiplayerPeer for both client and server are using only ENetMultiplayerPeer.new() and do not change any of the settings once created.

When testing the same server/client code on the same machine (Local Host) this random disconnection never happens.

I've tested it with both the server computer on an Ethernet connection and on a Wi-Fi connection. The client computer is always on a Wi-Fi connection.

In an MRP version I am not sending any RPCs either, just the initial connection from client to server.

Computer 1's specs are as described above
Computer 2's specs are as follows:
Godot v4.4.1.stable - Windows 10 (build 19045) - Multi-window, 1 monitor - OpenGL 3 (Compatibility) - NVIDIA GeForce GTX 1050 with Max-Q Design (NVIDIA; 30.0.15.1169) - Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz (8 threads)

Steps to reproduce

1. Open the MRP on two separate computers on the same network.
2. Start the server on one computer using the Start Server button displayed in the main scene of the project. Note the IP address printed to the console.
3. On the other computer, change the IP address field returned by ENetClient.gd getIPAddressToConnectTo() to the local IP address of the server computer.
4. Start the client connection using the Start Client (LAN) button displayed in the main scene.
5. Observe that the client successfully connects to the server in the console logs on both client and server. This may take a few seconds occasionally.
6. Observe the Godot's console on both client and server for the disconnect message. I never got the connection to last more than 5 minutes and more often than not it disconnected within 1-2 minutes.

Minimal reproduction project (MRP)

simpleserverclient.zip

[janavarro95]

I've tried adding

func _process(delta: float) -> void:
	if eNetPeer.get_connection_status()==MultiplayerAPI.CONNECTION_CONNECTING or  
 eNetPeer.get_connection_status()==MultiplayerAPI.CONNECTION_CONNECTED:
		eNetPeer.poll();

to both the ENetClient and ENetServer classes and while that does sometimes prevent the random connection, once I start sending data such as player positional data, this also breaks again with a disconnection issue.

[janavarro95]

After additional testing I have discovered the following

1. This bug only occurs for me when I have created/destroyed the client/server many many times. This can be reproduced by starting up the MRP described above, starting the client/server connection and then closing the game window over and over.
2. When doing step 1 repeatedly, I eventually noticed that the client would take longer and longer to connect to the server and sometimes the client connection would inexplicably timeout. Whereas at the beginning of testing the connection would happen almost instantaneously.
3. Unplugging and replugging in my router seems to "solve" this issue when I tried testing it or at very least, removed the initial connection lag as mentioned in step 2. As for why, I'm unsure as I'm unable to access my router logs/settings. My best guess is that perhaps because the connection is not cleanly closed when the game window is closed and that it leaves some sort of connection/data left that the router is listening in on which clogs up the router leading to unexplainable connection timeouts/losses for future connection attempts.

Point 3 leaves me suspicious that this may just be a local issue with my router, or perhaps a user error as in the MRP I don't clean up the connection when closing the game window. If the connection should be cleanly closed when the game window is closed with a notification in the root node of the SceneTree, that could possibly be a good solution.

func _notification(what:int)->void:
	if what == NOTIFICATION_WM_CLOSE_REQUEST:
           ##Cleanup Server/Client here.
           ##Would we need to call multiplayer.multiplayer_peer.close() or set multiplayer.multiplayer_peer=null ?