The "UWP Default Outbound Block Rule" of the Windows Defender firewall blocks all outbound traffic from the app. The Event Viewer reports a constant stream of events 5152 (Filter Platform Packet Drop) and 5157 (Filtering Platform Connection) failing the rule.
Adding a manual rule for the AppX package doesn't work, likely because the UWP default rule is more generic and takes precedence. This prevents any Win11 machine from joining a LAN game.
On Windows 10 however traffic goes through and the LAN game appears. Verified on at least 2 separate Win11 machines, one of which was connecting to the LAN game before upgrading from Win10 to Win11.
It's unclear if there's a UWP capability missing nor what's the difference between Win10 and Win11 here, but this effectively blocks all LAN games.
Im currently also having an issue with LAN games. Im on PS5 and my wife is on PC. Idk why but LAN games havent been working well lately. Sometimes my wife can join my world. Other times it doesnt even show up, which is more often then not lately