Last few games when I had been winning my opponent "aborted" the game. Is it possible for them to manually do it or did the server or something actually shut down?
Most of the time, the server aborts games when one player's connections are weak. However, there is an "Abort Game" button that can abort games manually. If you haven't seen it, you don't want to start using it. More than a few aborts will cost you games and put you in a special pool with cretins and malingerers.
Read the "Fair Play policy" from the Help and Support pages.
Last few games when I had been winning my opponent "aborted" the game. Is it possible for them to manually do it or did the server or something actually shut down?