Server online, but someone can't get in? Valheim join failures are almost always one of the six below. Work down the list in order — it's sorted by how often each one is the answer.
1. The join code is stale
The six-digit join code changes every time the server restarts, including the automatic restart that installs a game update. A code that worked yesterday is dead today.
Fix: open your Overview tab, find the newest registered with join code line in the console, and share that one. PC players can skip codes entirely and use Join IP with the host:port from your connection card, which never changes.
2. Game version mismatch
Everyone must run the same version as the server. The server updates itself on restart; players update through Steam or their console store. Straight after a patch it is common for one platform to lag the others by a few hours.
The message on their screen is "Incompatible version".
Fix: have the player check for a game update. If the server is the one behind, restart it — the update installs on the way up. If you'd rather hold the server on the old version until everyone has patched, set Auto Update to 0 on the Server Settings tab first.
3. Wrong password
The password prompt appears after the connection succeeds, so "wrong password" means the network part is fine.
Fix: copy the current password from the Server Settings tab and send it again. If you just changed it, the change only takes effect after a restart.
4. The server is still booting
Between Start and registered with join code, joins time out. A fresh world takes about 20 seconds to generate; a restart that also installs an update takes a minute or two.
Fix: watch the console; invite people once the join-code line appears.
5. Console player, crossplay off
PlayStation, Xbox and Switch 2 players can only reach a server that was started with crossplay enabled.
Fix: Server Settings → Enable Crossplay = 1, then restart. If crossplay is already on, check the console side: PS5 players should switch off the "PlayStation Network Only" toggle on the join screen, and Xbox players need the "allow play with people outside Xbox" privacy setting on. Full detail in Crossplay & Join Codes.
6. One player, weird symptoms
If exactly one player rubber-bands, disconnects or freezes on the loading screen while everyone else is fine, it's their side: Wi-Fi, a VPN, distance to the server's region, or a mod on their client that the server doesn't run.
Fix: wired connection, VPN off, verify game files, and make sure their client is vanilla if the server is. If they're on another continent, their ping to your server's region is what it is — moving the server closer to the group is a ticket away.
Still stuck?
Open a ticket from your dashboard with: the player's platform and exact error text, whether anyone can join, and the newest join-code line from your console. Those three answers usually let us solve it in one reply.