Fiber outages feel worse than regular internet outages somehow — maybe because you expect fiber to just work. When mine went down mid-workday, here’s the exact sequence I went through, from fastest checks to the ones that actually require patience.
Rule out a wider outage first
Before touching a single cable, check AT&T’s outage page or an app like Downdetector. If your neighbors are also affected, no amount of restarting on your end will fix it — you’re just waiting for AT&T to resolve it on their side, which in my experience takes anywhere from an hour to most of a day depending on what caused it.
Look at the ONT box, not just the router
This is the part people skip. Your fiber connection comes into your home through an ONT (Optical Network Terminal) — a small box separate from your WiFi router. Check its lights: green generally means things are fine, red means there’s a problem between your home and AT&T’s network that a router restart won’t touch. If you see red, that’s genuinely a call-support situation, not a troubleshoot-it-yourself one.
The restart — but give it real time
Turn off the router, then the ONT. Wait a full 60 seconds, not a quick count. Power the ONT back on first and let its lights fully stabilize before touching the router. I’ve had this alone resolve the issue more times than any other single step, but only when done in the correct order and with enough patience for the ONT to reconnect properly.
Check the physical fiber cable — carefully
Fiber optic cable is more fragile than a normal Ethernet or coax cable. If it’s been bent sharply, pinched under furniture, or damaged during a move, that alone can kill your connection. Don’t try to bend or reposition it yourself if you notice damage — this is one case where a technician visit is genuinely the right call rather than a DIY fix.
Factory reset, only after you’ve saved your settings
If the restart didn’t help and the ONT lights look normal, a factory reset on the router might. Hold the reset button for about 10-15 seconds. Just know this wipes your custom WiFi name and password, so have those written down beforehand.
Rule out a billing hiccup
This one’s easy to overlook when you’re focused on hardware. Log into your AT&T account and confirm there’s no payment issue or expired card on file — a lapsed payment can suspend service even though everything on your end looks physically fine.
Test on a second device
If only one device can’t connect, the ONT and router are probably fine and the issue is local to that device — try connecting via Ethernet directly, or test with a phone or another laptop to narrow it down.
When it’s time to actually call
If you’ve been through all of the above and the connection is still down, or the ONT is showing a red light, contact AT&T’s live chat or request a technician visit. Having your account details and a quick note of which lights you saw ready before you call speeds the whole process up considerably.
A few things worth doing once you’re back online, to avoid a repeat:
Keep the ONT and router in a ventilated spot — I had mine tucked in a closet for a while and it ran noticeably warm, which likely contributed to instability
Check for firmware updates in the router’s admin panel every couple of months
Switch your DNS to 8.8.8.8 or 1.1.1.1 if pages load slowly even when your raw speed test looks fine
Most AT&T Fiber issues really do resolve within an hour or two once you know where to look — the ONT lights specifically are the detail most guides skip, and they’re usually the fastest way to tell whether the problem is yours to fix or AT&T’s.
Tanimur Rahman is the founder of Internet Fix Guide. He writes step-by-step tutorials to help users solve WiFi, router, and internet connectivity problems quickly.