This is going to be long so forewarning.
How me and my friends usually fix this issue is to do the following which again is a pain in the rear but has yet to fail except on people who are on wifi only and cannot access their routers.
First both players go into your privacy settings and change EVERYTHING related to seeing, playing, or sharing with other players to everybody, yes everything.
Next, delete each other off your friends list and remove your profile from your xbox.
After that, turn off your console and unplug it for about 2-5 minutes, at the same time while it is unplugged, try to turn it on to make sure no left over juice is idling.
Go to your router in the mean time and login to the settings on a computer, hard wired preferred. After that check to make sure your xbox ones ports are open, all of them. Then proceed to take the last digit from the xbox IP address and put it into the dmz of your router which essentially throws it out of the firewall. Next after your router updates all of those settings and finishes rebooting, unplug your router and modem then leave them unplugged aswell for about 2-5 minutes. After the time has passed start by replugging in your modem, then router, and lastly the xbox, when your xbox reconnects check the network, it should be open if you did it all correctly and opened the right ports with the correct IP from the console. After it says open, redownload your profile and add your friend as a FAVORITE, lastly after all of that is done you will all see if you can reconnect to the game and then it's just a matter of instance hopping until yall slowly get into each others instance, the fastest way i'd say is to have your friend not in the us sit at a station and to have you and the other two us friends jump servers until one of yall land on his, then just keep rotating until you are all in. If it still does not work then you're just screwed lol.
