Valheim multiplayer has one unusual property that explains most join failures: the dedicated server is not authoritative. It relays RPC traffic and serves map data, while game logic authority sits with the clients in the areas they are interacting with. That design is why Valheim servers are cheap to run and also why the connection setup matters more than the server’s specs.
Three ways to play together
Friend-hosted. Someone starts a world from the main menu, everyone else joins through the Steam friend list. Simplest, no ports, and the host has to be online for anyone to play.
Direct dedicated server. A server started without -crossplay. Players connect straight to it, identity is by steamID64, and the operator is responsible for all internet routing.
Crossplay dedicated server. A server started with -crossplay, the default in the launch scripts that ship with the dedicated server. Connectivity goes through a relay, which means no port forwarding — and a different join method.
Capacity is the same in all three: up to 10 players, with enemies scaling to the group.
The two ports
| Port | Protocol | Purpose |
|---|---|---|
2456 (or -port value) | UDP | Valheim gameplay RPC |
2457 (or -port value + 1) | UDP | Steam query port |
Both bind to all IPv4 and IPv6 interfaces. The query port is always gameplay+1, so changing one changes the other implicitly.
For a direct server behind a private subnet you need to forward both UDP ports. Valheim Dedicated Server does not use UPnP or NAT-PMP, so nothing is opened automatically — a router that “supports UPnP” will still not help.
Crossplay: what actually happens
-crossplay changes the transport. Instead of accepting datagrams from players, the server talks to a relay and players talk to the same relay. The relay, public server advertising and multi-platform identities are all powered by Microsoft Azure PlayFab Party.
The consequences are concrete:
- You cannot join by LAN or loopback IP. There are no inbound listening ports in this mode.
- You join with a numeric join code, or with the external IPv4 address plus gameplay port. The IP is only an identifier for locating the relay — no port binding happens on the server locally.
- A domain name works only if it resolves directly to the exact external IP the relay sees. A CNAME or a proxied record will not.
- Expect more lag. The wiki states plainly that crossplay players are more likely to see lag, timeouts and disconnects, because of the extra hop and the geographic sensitivity it introduces.
Relay location is chosen by proximity or latency from a fixed Azure region list, which as of the Bog Witch update includes AustraliaEast, AustraliaSoutheast, BrazilSouth, CentralUs, EastAsia, EastUs, EastUs2, JapanEast, JapanWest, NorthCentralUs, NorthEurope, SouthAfricaNorth, SouthCentralUs, SoutheastAsia, UaeNorth, WestEurope and WestUs.
That list is the practical argument for direct mode: if your group is in a region without a nearby relay, direct plus port forwarding will be meaningfully better.
Which mode to pick
Pick crossplay if the group spans PC and Xbox, or if you cannot forward ports. Setup cost is near zero and you accept some latency.
Pick direct if everyone is on PC, you can forward two UDP ports, and you care about latency. It also gives you clean steamID64-based banning.
Pick friend-hosted if it is two or three people and nobody wants to run infrastructure. The cost is that the host’s machine has to stay on.
Why a friend cannot join
In order of how often it happens:
- Crossplay mismatch. The server runs
-crossplayand the player is trying an IP, or the server is direct and the player is trying a join code. Neither works. - Only one port forwarded. 2456 open and 2457 closed gets you a server that appears in the list but rejects connections.
- Version mismatch. Valheim validates a version code on connect. Server and client must match.
- Password or ban list. The server validates a password and checks banned and permitted lists on connect, so a stale ban entry looks exactly like a wrong password.
- Host offline. Friend-hosted worlds only exist while the host is in them.
Admin and moderation
Admin commands require the player’s steamID64 (or crossplay player ID) to be on the server’s admin list — renting the server is not the same as being on that list. Once you are: kick, ban, unban, banned, save and setworldmodifier all work.
Cheat commands do not work on a dedicated server at all. That is a vanilla restriction, not a config error; see Valheim console commands for the tier breakdown and the mod that lifts it.
Related guides
- Valheim hub — all guides for this game.
- Valheim console commands
- Valheim mods guide
- Valheim world seeds
- Valheim base building guide