Assetto Corsa Server Not Showing or Won't Let Drivers Join
Assetto Corsa failures tend to look like one problem: a server is absent from the lobby or a driver is rejected at the join screen. They are two different checks. First make the server advertise; then make the server's car, track and session content identical to every client.
Use the correct dedicated-server tool
The original Assetto Corsa (not Competizione or EVO) ships a separate Assetto Corsa Dedicated Server tool on Steam, app 302550. It runs acServer/acServer.exe from its own folder. On Linux, community wrappers and copied server files are common, so verify the current binary and compatibility layer before troubleshooting the configuration itself.
Make the server visible
The main file is cfg/server_cfg.ini. These are the values that matter for a normal public lobby server:
| Key | Typical value | What it controls |
|---|---|---|
REGISTER_TO_LOBBY | 1 | Advertise the server in the public lobby. |
UDP_PORT | 9600 | Race/game traffic. |
TCP_PORT | 9600 | TCP listener used by the server. |
HTTP_PORT | 8081 | HTTP/lobby service used by the server. |
MAX_CLIENTS | your grid size | Maximum connected drivers; keep it within the plan and content capacity. |
Forward the configured ports in the router and allow acServer through the host firewall. A common public setup forwards 9600 TCP/UDP and 8081 TCP/UDP. If your config uses different numbers, those numbers win. Wait a few minutes after launch before judging the lobby; use the game's direct-connect option with the server IP and port to separate lobby delay from a real network failure.
Stop content mismatches before the join screen
Assetto Corsa does not make a private mod pack appear by magic. The server names the content; clients must already have the same content installed, with the same folder names and compatible versions.
- Compare
CARS,TRACKandCONFIG_TRACKinserver_cfg.iniwith the installed car and track folders. - Check
entry_list.inifor entries that reference cars the server does not have. - Have every driver install the same mod release. A car with the same display name but a different folder or version is still a mismatch.
- Test with one stock Kunos car and track. If stock content works, add the mod pack back one item at a time.
Session settings that commonly block a league
Once the lobby and content work, check the session cycle: practice, qualifying and race blocks in server_cfg.ini. A race that never opens is often a closed IS_OPEN value or a malformed session section, not a port issue. Keep PICKUP_MODE_ENABLED, player slots and the entry list aligned with how your league actually starts.
Fast diagnosis
| Symptom | First check |
|---|---|
| Not in the public lobby | REGISTER_TO_LOBBY=1, firewall/router, then wait a few minutes. |
| Direct IP also fails | Use the exact UDP_PORT/TCP_PORT from the config and check the server log. |
| Lobby entry exists but “can't load information” | HTTP port 8081 (or your configured HTTP_PORT) and firewall protocol. |
| Driver is kicked for missing content | Exact car, track, layout and version; test with stock content. |
| Server starts then closes | Read the first config error in the log; blank values and invalid track layouts are common. |
Sources
- Assetto Corsa Steam Community: public server ports and lobby troubleshooting
- SteamDB: Assetto Corsa Dedicated Server app 302550
- Steam: the original Assetto Corsa
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