1. Power cycle ATT gateway - unplug router and modem, wait 60 seconds, let them reboot and see if that fixes it. DO NOT reset router to factory settings as it will loose all programing
2. Check cables and make sure everything’s connected
3. If that fails, call ATT support. (800) 924-9420. Just need to know my main phone number 404.434.3672
We can’t trouble shoot from our side unfortunately. If still having problems, let us know and we can come out the next day to fix it.