will not connect AT ALL

[Anixthegreat]

this is for my lil brother iv installed everything on his computer just like on mine but it wont let hin connect to the game at all but iv put the same version on my dads computer but works fine for my farther please help he wont stop bugging me about it and its pissing me off

[Death]

So at which part doesn't it let him "connect"?
When the game starts? at the main menu? can't join/create games?