"Not Connected to Xbox Live" on MCC PC - HELP!!!!!

I’ve been trying to get multiplayer to work for days and haven’t been able to do so. I’ve reinstalled the game several times, made sure all the ports are open, tried turning the relay on and off, signing in and out of my profile, everything. I’m on Windows 7.

Singleplayer works fine but I always get “Not Connected to Xbox Live” whenever I try to access any kind of multiplayer. I can see the pings of the servers fine in the settings but I can’t play.

Please for the love of god help me it’s been three days and I just want to play Halo.

Please help me with this. I got no replies.