Valheim "Failed to connect" to a friend's server (fix)

Update the game, and ask the host to update theirs, to Patch 1.0.14 or later (1.0.20 is the newest as of October 18, 2026; neither it nor 1.0.17 lists a connection fix, so 1.0.14 is still the floor). Iron Gate's 1.0.14 notes say it disabled biomedata caching to fix a cache that could get stuck in an invalid state and make joining remote servers impossible. The notes do not say this is the cause of every failed connection, and Iron Gate says a patch can take a few days to reach every platform.

If the server runs on the crossplay backend, join it by public IP address and port, a join code, or the server list. Iron Gate's dedicated server guide says "it's not possible to connect using a local IP address or a loopback IP address" on that backend.

If the server is a dedicated server on the Steam backend (started without -crossplay), its port range, 2456-2457 by default, has to be reachable from the internet, which means forwarding those ports on the router. Iron Gate's dedicated server guide says a crossplay-backend server needs no port forwarding.

If everyone in the group is on Steam, ask the host to start the world with crossplay turned off (the option sits next to the start button), delete the old server entry from your Favorites tab, and join through a Steam friend invite from the Friends tab. A Steam Community moderator gave this answer in the December 2023 thread, but that poster didn't report back. After Patch 1.0.20, the poster of an r/valheim thread (October 18), where one of six players got "Failed to connect" and "couldn't resolve join code", said: "I just turned off crossplay and port forwarded and now he can join again!" A dedicated server without crossplay needs ports forwarded (see the step above). Iron Gate hasn't commented.

Test the link: the same moderator suggested running a buffer-bloat test (speed.cloudflare.com) and typing /ping in the Valheim chat once you get in, to see whether latency is high or unstable, and noted that Wi-Fi connections are more often problematic than wired ones.