Concerning the "+2" bug
Aparrently C2 does not like when your hostAlias is composed of 1 letter only. He ads two when you put only 1 character. It does not do it when you put at least 2 character (just try nickname "a" for the host, and enter a second time as a peer)
The problem is that my friend cannot play. And it's not just my friend. It was 3 different persons. I was thinking of an antivirus issue but i think it would have told that it blocks something. And i have one too so I don't know.
And he can connect, it just does not work with peer assignement for him, which is strange.
What people get is. Player 1=host and 3 times Player 2=peer when they open hosted file 4 times and joining the same room with different nicknames.
What I'm kindly asking to do if people want to help me is.
Firstly: use this link to enter in the same room as 4 different peers on your computer and tell me if each player has a different number (player 1, player 2, player 3, player 4) http://jockey-miners-47580.bitballoon.com/
Secondly: do the same with a different person. So first try to connect as a host and tell the other person to connect 3 times in the same room. And ask him if he has a different player each time. Then invert the role, ask him to be host. If it works i'm pretty sure it's not a multiplayer plugin glitch.