If you are having networking-related issues with Xbox Live, please first check the status of Xbox Live services.
If you are still unable to connect, check Troubleshoot your Xbox network connection at Xbox Support.
If you are having internet trouble that is not specific to Halo or Xbox Live, sometimes power cycling can fix the issue. To power cycle:
- Unplug the power cable to your modem for 30 seconds, then plug it back in.
- Unplug the power cable to your router for 30 seconds, then plug it back in.
- Hold the power button down on your Xbox One console for 10 seconds.
If you have tried everything above and you still have networking-related issues with Xbox Live, please submit a ticket.