Diving into Halo 3’s campaign with an online friend (or several) sometimes simply doesn’t…work. You’ll send out the invites and group up, pick and load a mission, and then the game abruptly hangs before kicking you to the main screen. Or you’ll get to play for a short while, and then everything freezes and boots you.
Either way, you get torn apart and can even lose your progress, both of which are irritating as hell. And this experience isn’t isolated to Halo 3—it can happen with other Microsoft games that rely on Xbox Live servers for multiplayer too, be it the rest of the Master Chief Collection or Forza.
The problem is usually related to network address translation (NAT) and Windows 10’s Teredo service. As a networking issue, it can be a little nebulous to solve, as the reasons for the trouble vary from person to person. To help, we’ve gathered all the major troubleshooting steps you can take (and have had to try ourselves) to fix the problem.