Can't play the same game at the same time in the same house

I just recently moved in with a buddy of mine. We both have our own Xbox One console. We can both play the same game, like Halo 5, at the same time. But once we try to play in the same lobby, it disconnects one or both of us. I've seen many comments online
about using UPnP to connect both at the same time, but he has an AT&T U-Verse router, which doesn't support that. Does anyone know of a way that we can both play the same game at the same time?

:)

 

Unable to play MW3 on 2 Xboxes at the same time, in the same house?

As per my FAQ you can't portforward DMZ your way around this problem

 

Unable to play MW3 on 2 Xboxes at the same time, in the same house?

Actually there are 3 xboxes in the house, have a netgear router, and for as long as we have had the 3 xboxes it has never been a problem with all 3 on lve at the same time.

Until now.

With one on MW3 when another tries to go on and play you get to the lobby and it then continually searches for games starting at <50MS going all the way through to continually searching with no limit and it's always 0/50.

Activision say: Thank you for calling Activision Support. I apologize about the issue you are having. This issue occurs when 2 consoles are useing one router to connect to Xbox Live. Routers are only made to have one console connect and play on them properly.
You can also try to open ports to help this issue, but again, routers are not made to have two consoles going on at once. If he gets this issue even when signing on alone, opening ports could help.

I think they are talking rubbish as the issue is on with MW3, no problems with MW2 at the same time.

I told them because I couldn't get on MW3 I tried another game, Battlefield 3, and could play that no problem, so the issue is quite clearly with MW3 in my opinion.

Anybody have similar problems or have any idea of a fix that I could try, thanks.