Cannot play multiplayer-private or public- after 1 day of purchase

[Frank Car Eater]

randomly syas ''connection to server failed'' and ''connection to host lost'' when i try to join a game, this is ♥♥♥♥♥♥♥♥, i bought this game yesterday with a friend and the multiplayer worked fine.

and for no reason it stops working, also port forwarding doesnt work for me.
any leads?

[Trayzard]

yep. Multiplayer not working at all. When i wanna join a Online Game it says "Cannot connect to Matchmaking Server"