Linking failed with a server error or a timeout

That is the game server not answering in time, not a problem with your account. Nothing was changed, and trying again in a few minutes usually works.

If it keeps failing, the game service may be under maintenance — check Announcements. Where a tournament's registration is about to close and linking will not go through at all, tell us before the deadline rather than after it; afterwards the roster is locked and there is nothing anyone can add you to.