Valheim crossplay not working: can't join, PlayFab error (fix)

Match the backend. A dedicated server started without the -crossplay argument uses the Steam backend, so only Steam users can see and join it; with -crossplay it runs on the crossplay backend (PlayFab) and players on any platform can join. This is from Iron Gate's dedicated server guide.

Join with the join code: the host opens the pause menu, clicks the code to copy it and sends it; the friend goes to Join Game, presses Add server and pastes it. A crossplay server can also be joined by public IP and port or from the server list, but not by a local IP or loopback address (Iron Gate's Crossplay FAQ and dedicated server guide).

On Xbox, the console and the server both need crossplay turned on to join a dedicated server. If you cannot find the crossplay option, Iron Gate's Crossplay FAQ says parental-control settings may be hiding it.

Port forwarding differs by backend: a crossplay-backend server reaches players through a relay and needs none, while a Steam-backend server needs its port range (default 2456-2457) reachable from the internet.

If everyone playing is on Steam, start the world with crossplay off and join through a Steam friend invite. A Steam Community moderator gave that answer for failed connections in a December 2023 thread; Iron Gate has not confirmed it.

If the server log shows PlayFab errors, check Microsoft's PlayFab status page at status.playfab.com for an open incident. The page exists and is Microsoft's, but there is no source tying a listed incident to Valheim join failures, and no confirmed fix for a server that cannot reach PlayFab.