Hello
A common issue with rf1, not sure what the problem is though. it seems to me matchmaker-server reboots frequently, maybe once a week and once it does problems are over.
I usualy sit it out and cross my fingers no problems arise just before a league-race. had that once and it was quite dissapointing.
But generaly it doesn't happen enough to be a major problem though, its just once in a while.
Some say rebooting rfactor also helps but never for me, try it anyways i'de say.
If you have servers you visit regurarly or maybe your own, then connecting via direct IP will also help.