UPNP for dedicated servers

On dedicated Minecraft servers, the mod uses UPnP to open the port automatically, so the server can accept players from outside the local network without manual router setup. The port is opened when the server starts and closed when it stops, and a server owner can check from an online port checker that the port is reachable. The mod is aimed at dedicated servers and is an alternative to LAN-style hosting, which is different from how single-player worlds are shared.

The mod primarily wraps the WaifUPnP library and binds its functions to the server lifecycle and to a command. The bundled library was modified slightly to log errors and to implement some pending pull requests from the original project, and the project includes bugfixes that forks did not carry over. Fabric API is required, and the mod is published for Fabric and NeoForge.

It runs on the server only, so players join without installing anything. Files cover game versions 1.21.11 – 26.2 across five release versions, and the mod is released under the MIT License, so the source is open. Public links exist for the source code and the issue tracker. The latest Fabric and NeoForge builds, 4.0.0, target 26.2 and do not support 26.1 or 26.2 mappings in the way earlier notes suggested; check the file list for the exact version.