Cant Connect to 1 specific friend for multiplayer

So about a year ago this issue started with one specific friend of mine on xbox, to where we try to join each other on any given game and it just does not work, we dont get error codes, we simply cannot connect to each other. we have tried all the basic
solutions, such as power cycling, wifi resets, port forwarding, etc.. both of our nat types are open, and we dont have any issues at all with anyone else, its just between us 2. we can join other people as a host and this sometimes works, but for games such
as Dark souls, this doesnt work at all. most of the time we are lucky if we can even manage to get into a party together without constantly getting the "connecting" message. I hope someone has a solution as I have tried the microsoft xbox "experts" and not
a single person out of like 6 conversations could help me.

:)