Some one help me with this

[(XBOX)RapidFire747]

I badly need help with this so here's the story

my friend who lives in Alberta that I play with on Xbox and I live in BC Canada and we try to do a mission but when I invite him through Xbox it says I invited him to halo 5 and it works just fine when I invited him through the game but when invited me to a game I can't join and when joins we go 5 secnds into the mission and his screen goes black and he disconnects from the game the same for the other way around as well and we have both tried everything but nothing we know of seems to work if the developers or players read please tell me if you know how to fix it