Can't connect to one specific player

okay I have been trying to play Xbox with my friend but for some dumb reason I can't connect to his games and he can't connect to mine. We have tried playing many games together with private sessions but they all seem to say connection lost or the host has
left the game. I don't understand this because we can both easily connect to our other friends and the only way we can play with eachother is if one of our friends is the host of the game and we join them. I have tried port forwarding and it hasn't worked.
I have also contacted Microsoft support countless times and all they give me is pointless troubleshooting solutions that never work. PLEASE FIX YOUR SERVERS MICROSOFT.

I am wired

He is wireless

My NAT type is open

His NAT type is open

We have tried different connections but it still doesn't work

I REALLY do not want to purchase a new Modem/Router and still not have the problem go away

:)

 

Not connecting

Can't connect in what way, online to play multiplayer? The game won't open? Please be specific as possible and someone can help.

 

Can't connect to specific friend on Xbox one games.

Alright. I've scoured the internet looking for a solution, to no avail. When trying to connect to one of my friends in any of the games we both own, first we have trouble connecting in party chat, then once we miraculously fix that (still cuts out from time
to time) we can NEVER manage to join each other's session, no matter who is host. Both of us have checked privacy settings, both of us are infinitely sure our NAT is set to open, we're both on the same alternate ports, we've tried almost everything short of
calling our ISPs. Any help is greatly appreciated.