Narofu

I need some serious help with Halo 5. I have 2 xbox ones and when me and my friends try to play them on the same connection we will be fine a few minutes but most of the time all we do is lag out and cant play. When one xbox is lagging the other one can play and when that one can play the first one cant. I have them both on a wired connection straight to the modem and my ISP is intermountain cable. They opened all the xbox live ports i needed opened for me.. When we only play as one xbox we can play. Any solution would be much appreciated, I just want to be able to play halo 5 with my buddies.