Assetto Corsa Connection Issue The Server Seems To Be Unavailable Fix Today

If the official launcher continues to fail:

The "server seems unavailable" error appears most often because your router is blocking the ports Assetto Corsa needs.

By default, Assetto Corsa uses UDP Port 9600. However, if you host regularly, you need a range of ports. Here is the official port requirement:

| Protocol | Port Range | Purpose | | :--- | :--- | :--- | | TCP | 9600 | Initial connection & server list | | UDP | 9600 (default) or 9600-9650 | In-race car positions, chat, telemetry | If the official launcher continues to fail: The

Assetto Corsa relies on Steam’s networking API. Try these:

This is embarrassing when it happens, but worth mentioning.

In the online lobby list, ensure you haven’t accidentally filtered by: Ensure both Private and Public boxes are checked for each

Clear all filters and refresh. Sometimes the server is available – you just hid it from yourself.

The error sometimes stems from your ISP blocking P2P server lists. Try using a free VPN just to fetch the server list, then disconnect once you’ve joined a race.

If all else fails, the Assetto Corsa online community is huge—search for your specific combination (e.g., “CM + Windows 11 + server unavailable”) on RaceDepartment or the official Assetto Corsa subreddit. More often than not, someone has already solved your exact scenario. Assetto Corsa relies on Steam’s networking API

Final tip: Don’t ignore the time of day. Server list providers occasionally have daily maintenance between 04:00–06:00 GMT. Waiting an hour sometimes fixes everything.

This is a common issue in Assetto Corsa that usually boils down to either network configuration, version mismatches, or the server actually being offline.

Here is a helpful post format you can use or follow to diagnose and fix the "Server seems to be unavailable" error.

Even with perfect router settings, Windows itself might shoot down the connection.

Some ISPs use "Carrier Grade NAT" (CGNAT), which breaks AC entirely. You cannot port forward CGNAT.