Fault-finding
No internet after the power comes back
Equipment that lost power rarely comes back in the right order. Power the ONT first, wait for its lights to settle, then the router, then switches. If it still fails, the ONT may not have re-registered — and in this climate a failing power adapter is the commonest hardware cause.
Written and reviewed by our networks and fiber bench · Last reviewed
Order matters when everything restarts at once
When the grid returns, every device powers on simultaneously and the router often looks for a connection before the ONT has finished registering. It then caches the failure. Powering them in sequence — ONT first, wait for a steady light, then the router — resolves a large share of these without any fault existing at all.
Read the ONT's lights before touching anything
A steady power light with a red or flashing loss-of-signal indicator is an optical problem and belongs with the ISP. A normal set of lights with no internet is your router or the session. The lights split the diagnosis in seconds and save an unnecessary call in one direction or an unnecessary reboot in the other.
Power adapters fail more than the boxes do
Repeated outages and voltage sags are hard on small switching adapters, and a failing one produces exactly this: works sometimes, dead after a cut. Substituting a known-good adapter of the correct voltage and polarity is a quick test that resolves a genuine share of apparently dead ONTs and routers.
Put the network on backup and stop having the problem
An ONT, a router and a small switch draw very little, so a modest UPS keeps the whole network alive through a normal cut. In a house that already has a hybrid inverter, moving the network onto the backed-up circuit costs nothing and removes this fault permanently rather than repeatedly fixing it.
Why does my internet not work after load-shedding?
What order should I power things on?
ONT first, and wait until its lights are steady rather than counting seconds — it needs to register with the ISP before anything downstream can get a connection. Then the router, then any switches and access points. Doing it in that order fixes most post-outage failures with no intervention beyond patience.
The ONT has a red light. Is that my problem or the ISP's?
A loss-of-signal indicator means no optical signal is arriving, which is on the ISP's side of the equipment in almost every case — a cut or damaged fiber, or a fault at their end. Check that the fiber connector at the ONT is seated, then raise it with them rather than restarting the router repeatedly.
Should the router be on a UPS?
Yes, and it is one of the cheapest quality-of-life improvements available. The whole network draws very little, so a modest UPS carries it through a normal outage — which means the connection is already up when the power returns instead of needing a sequenced restart every time.
Rather have it done?
Getting fiber into a building means checking which providers actually reach your street, running the drop from the pole or duct to a proper termination point, and handing over a connection that works on your own equipment. Internal work runs PKR 12,000 to 45,000, separate from whatever the ISP charges.
Fiber internet connection for homes and offices in Islamabad — prices and scope