@Hio: I’ve created a local network multiplayer example here: https://github.com/britzl/defnet/tree/master/examples/multiplayer
The example will listen for an instance of the application acting as a host or announce its presence as a host for other clients to connect to if no host is currently broadcasting on the local network. When the host receives a connection its is forwarded to all the other clients. The clients themselves communicate directly with each other and repeatedly send a heartbeat message to the host. If a client is shut down or for some other reason is unable to send heartbeat messages it will be removed and the other clients will be notified.
There’s plenty of room for improvement, and I’m really no expert in network coding, but hopefully it will at least give you an idea!
