In CM, go to Settings > Content Manager > General and ensure your "AppID" is correct (usually 244210). 🏎️ Advanced Troubleshooting
If you want, tell me whether you’re trying to join or host, which Assetto Corsa title you use, and whether you’re on PC/console — I’ll provide a tailored port list and specific router steps for common models. In CM, go to Settings > Content Manager
(not hosting), skip port forwarding. But check this in Content Manager: which Assetto Corsa title you use