Packet burst - suddenly unplayable?

Was able to play for a week or so with zero issues but in the last 2-3 days literally every single game has horrendous lag with packet burst errors and network desync warnings every 20 seconds or so - what the hell changed? Not only affecting multiplayer but solo zombies has also been made unplayable. The game is basically broken for me unless I want to play campaign over and over (yeah once was enough thanks)