After being told this game still has an active player base very recently, I haven't been able to connect to any sort of lobby... for unranked adventure, free-for-all racing, etc..
I can do Rivals and it can pull records of players, so there is a smidge of a connection to some online stuff, but just not a serve to join players into the same room for live activities. In two connection failed attempts, one failed connecting to West Europe and another to the Australia region... which leads me to think the North America server is either not available or next to no players left playing here.
If you're still playing, where in the world are you playing from?