Valheim Friends Can't Join? Crossplay & Port Forwarding Guide
If friends cannot join your Valheim world or the game says “failed to connect,” do not start by opening ports. First decide which connection path you are using: a Steam dedicated server, a normal hosted world, or Crossplay relay.
That choice changes the fix. A Steam dedicated server often depends on your router and firewall. Crossplay relay depends more on relay status, platform login, invite method, and matching versions. Check NAT before you spend time on port forwarding, because some home networks are not reachable from the public internet.
First decide where the failure is
Valheim uses more than one joining path, so the same player-facing error can point to different fixes. Split the symptom before you change the router.
- LAN works, but friends outside your home cannot join a Steam dedicated server: treat it as public reachability, forwarding, and firewall.
- Crossplay is enabled: check relay state, platform login, invite method, password, and version match first.
- Nobody can join, even on the same LAN: fix server startup, world loading, password, version, and local firewall before router settings.
- Direct IP joining works, but the server is missing from the browser: stop changing ports and troubleshoot discovery.
If outside connections fail, check NAT and public reachability
Run the test on the same device and network you use for Valheim. The result helps separate ISP/router reachability from game, firewall, and platform problems.
| Result | Meaning for hosting or co-op | Next step |
|---|---|---|
| Full Cone / Open | Usually suitable for inbound connections or direct sessions. | Check firewall, ports, server config, and game version. |
| Restricted / Port Restricted | May work, but success can vary by game and peer. | Try UPnP or manual forwarding, then retest. |
| Symmetric NAT | Often unreliable for peer-to-peer or home-hosted sessions. | Disable VPN/proxy tools, change networks, or use hosting/relay. |
| CGNAT / no public IPv4 | The public internet usually cannot reach your home router. | Ask for public IPv4, or use a VPS, hosted server, or relay. |
If outside players can reach the host, apply the game-specific fix
Once the host network is reachable, the Steam dedicated server fix is straightforward: send Valheim traffic to the right machine and allow the server process through the operating-system firewall. If you are using Crossplay relay, this is usually not the first lever.
UDP
2456-2457Default dedicated-server range in Valheim guidance. Forward it only to the server LAN IP, and mirror the same allowance in the OS firewall.
- Give the server device a stable LAN IP before creating router rules.
- Forward UDP 2456-2457 to that LAN IP, not to your public IP.
- Allow Valheim Dedicated Server, or the exact UDP range, through Windows or Linux firewall.
- Retest from mobile hotspot or another outside network. Same-LAN tests can be misleading.
If direct joining works but the symptom remains, check the next layer
Server browser visibility is not the same as connection reachability. If friends can join by direct address, your next checks should be server discovery, Crossplay consistency, and session details.
- Try direct IP:port joining before relying on the in-game browser.
- Confirm the client and server are on the same Valheim version.
- Check the password, world name, public setting, and startup parameters.
- Keep Crossplay enabled or disabled consistently across the server, platform account, and joining method.
When router changes will not fix it
Stop editing router rules when the problem is outside the router layer. At that point, changing the hosting path is more useful than adding another port rule.
- The host network is behind CGNAT or does not have a public IPv4 address.
- The host has Symmetric NAT and direct Steam hosting remains unreliable.
- Crossplay is enabled and the remaining failure follows account, platform, version, password, or invite flow.
- Direct joining works and only the server browser is unreliable.