Thanks for the fast reply!
Your relay has probably chosen some overloaded guards. The problem comes from the extra load on those machines, not your relay. Your relay will eventually try other guards.
Are you sure it's not overloaded? It might be worth checking the logs, inbound connections, RAM, and CPU after it has been running for a few days.
Yes, the relay is working fine - the only problem was the connection limit due to some OS-level limits.which is why I had to restart the relay in the first place.
Ignore the warning messages unless your relay is having problems.
Ok, I'll do :) Once one successful circuit was established, there were no warnings any more. It just took some time - but I cannot tell if the relay switched guards or if the guard nodes finally managed to accept a connection request, since I didn't check the guard node set prior to restarting.
Regards, Dark