As far as servers go one of my biggest pet peeves is “Connection timed out: could not find server.”
Even though you saved the server as one of your favorites they never show up. “Favorites” is always grayed out. (Even after saving it on Steam as a favorite.)
Cannot, in most servers, access “Admin without a password not given.”
Therefore, I prefer to play in single-player / co-op.
Just sayin’.