Server's full

Yeah, this is a thing that's going to happen a lot now. A whole frickload of people just found out about the server and want to try it out, so you're often going to have trouble joining in. Just be patient and try not to bug the staff too much about this, they're aware of the massive influx of players and are working on ways to support this increased load.

If the server is full, please avoid trying to connect!

Instead, refresh the listing of servers occasionally and see if the number dips below 30 and then attempt to connect. This avoids filling the ingame chat with <your_name> is joining the server, which will annoy the heck out of people racing.