Not me. I can play the game with no problem but my friend can’t play the game because of this error and what is even more interesting is that he once played it somehow.
He can not connect to Multiplayer or Firefighter. However; he(and we) can play campaign and custom match between us, somehow.
Please. Find a solution.
We tried almost every possible fixes like port forwarding, parental stuff, deleting hosts file and etc. It makes no sense since just as I said, he managed to play the multiplayer for once somehow. Nothing has changed, but he started getting that error.
I just want to play with him. What’s the matter? 
What’s the solution?