LAN discovery
LAN discovery lets a game find other games on the same local network on its own, usually with a small broadcast beacon, so nobody types an address.
Also called local network discovery, LAN game browser, UDP broadcast discovery.
Typing an address to join a friend in the same room is a chore, and when it fails the game rarely says why. With LAN discovery, the hosting game announces itself on the local network and any game that's looking lists what it hears, so joining is one click.
Why do some LAN finders miss games?
A broadcast has to go to the right address for the network you're on, and that depends on the network's size. Godot reports your address but not the size, so a finder that assumes a home router's /24 network fails on a phone hotspot, which is a much smaller network. Sending to the broadcast address of every common size fixes it.
LAN discovery in Mytheria
The host sends a small beacon once a second, at most 512 bytes, to every network size from /16 to /29 plus the limited broadcast and loopback. A game that goes quiet drops off the list after four seconds, and the beacon is only a hint: joining still goes through the normal handshake and the host's own checks. We released it as a free Godot add-on: LAN Discovery, MIT licensed.
The full post, with clips and demos LAN multiplayer in Godot: finding a friend's game on any Wi-Fi