Can't Join an OpenTTD Server? Version, NewGRF and Connection Fixes

If you cannot join an OpenTTD server, the cause is almost always one of three: your game is not the exact same version as the server, you are missing a NewGRF or other content the game uses, or the connection cannot get through and you declined the relay. Match the version first, then let the game download missing content, then join with the server's invite code and allow the relay if asked. Passwords and full servers cover nearly everything else.

Fix 1: Exact same version

OpenTTD multiplayer needs exactly the same version on server and client. Not just the same major release: 15.2 cannot join 15.3. In the server list, a server running a different version is shown greyed out or marked, and joining is refused.

How to match:

• Check the version on the server list entry, or ask the admin.
• Check yours on the main menu.
• Download the matching release from the official OpenTTD downloads, or on Steam use the beta branches to pick an older release.
• Remember both sides move. A new stable release (and OpenTTD ships them often, with 15.x out and 16.0 in beta in 2026) means either everyone updates, server included, or everyone stays put.

Testing releases (beta, RC) do not mix with stable either. If one friend runs a nightly or beta build, they will not get onto a stable server.

Fix 2: Missing NewGRFs and content

The server's game may use NewGRFs (vehicle sets, industries, graphics), a base set, AIs or a game script. Your client needs the same NewGRFs, at the same versions, to join.

1. Select the server in the Multiplayer list.
2. Click NewGRF Settings (or the info button) to see what it uses. Missing ones show in red.
3. Use the option to look for the missing content online. OpenTTD downloads it from BaNaNaS, its content service.
4. Join again.

If content will not download, the server may use a NewGRF that is not on BaNaNaS, or a newer or older version than BaNaNaS offers. Ask the admin where they got it. Admins: stick to NewGRFs from BaNaNaS so players can always fetch them in game.

Fix 3: Use the invite code, and allow the relay

Since version 12, OpenTTD connects players through its Game Coordinator. Every server that is not local gets an invite code, starting with +. Joining with it works in more situations than typing an IP:

1. In Multiplayer, choose Add Server.
2. Enter the invite code, for example +a1b2c3, or the IP and port.
3. Join.

The coordinator tries a direct connection first, then a technique that works through most home routers (STUN), and as a last resort a relay (TURN) run by OpenTTD. Whether your game may use the relay is your client's use_relay_service setting, and by default it asks. If you click no, or the setting is set to never, a server you cannot reach directly stays unreachable. Allow it, at least for that server.

The relay adds a little latency, which is fine for a transport game.

Fix 4: The server is not listed at all

If the server does not appear in the public list, the problem is on the server side:

• server_game_type must be public to be listed. invite-only hides it but still allows joining with the invite code. local (the default) is LAN only.
• Old configs may still contain server_advertise and lan_internet, which current versions ignore. Set server_game_type instead.
• The server's game port, 3979 TCP and UDP by default, should be reachable for direct connections. With the Game Coordinator, players can often still join through the invite code even when the port is closed. Our port forwarding guide covers opening it.

Admins can change it live in the server console: setting server_game_type public.

Fix 5: Password, full server or wrong company

• Server password. If asked for a password, it is the server_password from the server's secrets.cfg. It is case sensitive.
• Full. max_clients counts players and spectators. max_companies caps companies: if it is reached, you can join as a spectator or ask to join an existing company.
• Company access. Since OpenTTD 15.0 there are no company passwords. To join a friend's company, they invite you from the Online Players window. Until they do, you can spectate.

Fix 6: Stuck downloading the map

When you join, the server sends the whole map. Large maps with many vehicles take time, especially on slow connections. The server pauses during the download if pause_on_join is on. Wait it out before giving up; if it fails every time, check your connection and that the relay is allowed.

Quick diagnosis

For admins: keeping joins painless

Pin the server version and tell players which one it is. Use only BaNaNaS content. Set the server to public, or invite only with the code posted in your Discord. And keep a named save before any version change, since moving a map to a newer version is easy, but going back is not.

On an OpenTTD server from GamezServers, the server name and list visibility are panel settings, and openttd.cfg and secrets.cfg are in the file manager. A new server installs the current stable release. When a new one comes out, email support@gamezservers.com with the version you want, and we reinstall the server on it with your saves kept, so the whole group can move together. Our console commands guide covers the admin side.

FAQ

Why can't I join an OpenTTD server?

Most often your version is different from the server's, or you are missing a NewGRF it uses. Match the exact version and download missing content.

Do OpenTTD versions have to match exactly?

Yes. Client and server must run the identical release, including minor versions.

What is an OpenTTD invite code?

A code starting with + that the Game Coordinator gives each server. Joining with it can get through routers that block direct connections.

How do I join a company on an OpenTTD server?

A member of that company invites you from the Online Players window. Company passwords no longer exist.