Impossible to start multiplayer game

Greetings everyone.

We tried to play Starcraft Remastered with a friend in 1v1 via battle.net

As soon as he joins the game, it is impossible to start it, the “OK” button is grayed out. When I am alone I can start the game. And we tried the other way around, he can’t start a game even if he’s alone in it, as a host. Of course I already played multiplayer multiple times so the issues comes from his side.

Of course the firewalls are ok etc…

I haven’t found this problem anywhere on the forums. Anyone has an idea to solve this ?
Thank you

(copied from tech support, maybe I will have more reach here)

IT HAPPENS. I had loads of connectivity issues. Still do. Starcraft sucks. I came to complain and I can’t even stop complaining so sorry if im not answering your question. I just got my ass handed tome by a computer and it wasn’t even fair. Protoss is just overpowered. Stupid shields and stupid dragoons and stupid carriers and stupid templars and stupid arbiters. Just keep trying to connect. U’ll probably have to wait another day cause starcraft sucks.