I have the same problem. It started 4 days ago, it was working perfectly fine the day before. I haven't been able to join a single match since.
I can only play in custom games. When the map is loading in multiplayer it just kicks me out saying "Connection interrupted" and literally no information about it. I've tried just about everything; Restarting Pc, restarting modem, verifying game files, reinstalling the game, changing my NAT, I also asked for help on steam forums but got nothing.
Honestly wtf? I just want to play the -Yoinking!- game, I have dozens of other multiplayer games and I have no issue when joining. Can we at least get a -Yoinking!- response from 343? What kind of customer service is this? Jfc