HALO 3 CUSTOM GAMES DONT WORK

Since the latest update, I haven’t been able to play any form of HALO 3 custom matchmaking for me and my friends. as soon as i get the game all qued up with me and my friends we get the expected blueprint of the map before the game loads only to be sent to a MCC loading screen then subsequently booted. The next screen that follows says “game over” or “unable to join gaming session”…… please tell me how is it possible that a patch could make an entire segment like halo 3 multiplayer not work entirely? this game has been out for 4 months and were still experiencing problems? i found the MCC collection to be a godsend….now i see it as a waste of money seeing as i can’t even use the game i purchased. who gave this game such a short deadline so as to not work out all the kinks?