Plutonium

So I've played with my friend on a custom lobby countless times, him connecting to me, I have my port forwarded, upnp enabled and I usually have no problems with any of it.
I had to factory reset my pc, downloaded plutonium again, same account and all that. and now, we can't play in a custom lobby. we can find a server online but whenever he tries to connect to me (dosn't matter if it's from the friends list ro with the command connect ip:4976) he gets a message "joining game session" that disappears after a couple of secconds and even if you wait after that, it dosn't connect.