How to keep Wi-Fi and internet on during a power cut (2026 guide)
Your router needs only 10–30 watts — the trick is keeping both the router and the fibre ONT powered. Five working setups from a ₹500 power bank to whole-home inverter circuits.
Quick answer
- A router + fibre ONT together draw only about 10–30 W — tiny compared to fans or TVs.
- Fibre internet dies at the ONT (the box where the fibre terminates), not at the router — both need backup power.
- A USB power bank with the right cable can run many 5V/9V routers for 4–10 hours; an inverter covers the whole home including the ONT.
Why your internet dies even with a charged phone
Home fibre internet has two powered boxes: the ONT (optical network terminal where the fibre line terminates, usually near the meter or entry) and your Wi-Fi router. A power cut kills both, so even a fully charged phone shows “no internet”. Mobile data is the fallback, but it is metered and slows down exactly when the neighbourhood is also on it.
The fix is to power those two small boxes through the outage. At 10–30 W combined, they are the cheapest resilience in the house — a fraction of what fans or a TV need.
Setup 1 — The ₹500–1,500 power bank trick
Most routers are powered by 5 V, 9 V or 12 V DC adapters. A USB power bank with 5V/9V/12V output (PD or QC) plus the right DC cable can run a router directly for many hours: a 20,000 mAh (≈74 Wh) bank holds roughly 50+ Wh usable, which at 12 W is 4+ hours, often much more since routers average below their rating.
Check your router’s voltage and plug size before buying; a wrong-voltage feed can damage it. This is the cheapest work-from-home insurance and also covers the ONT if it accepts DC input (many do, but some need mains — see setup 2).
Setup 2 — Put the router and ONT on the home inverter
If you have an inverter, the cleanest solution is a dedicated socket wired (or extended) to the router and ONT so both stay live during cuts. Ask your electrician to put the “network points” on the inverter circuit — it costs little during installation and means zero manual swapping during an outage.
Do the math: 20 W for 4 hours is 80 Wh — a rounding error for a 1,200 Wh-class battery. The internet is effectively free to keep alive; the mistake is only forgetting it when sizing or wiring.
Setup 3-5 — Small UPS, solar DC, and mobile fallback
A 600 VA offline UPS (the kind sold for desktops) runs a router + ONT for 2–4 hours and switches seamlessly — ideal for flats where wiring changes are not allowed. Solar-direct kits (small panel + battery + DC router feed) exist and suit long daily outages, but the payback only makes sense when cuts are frequent and long.
And always keep the free fallback ready: know your phone’s hotspot password flow, keep one data pack active, and test it before the next cut. During area-wide outages, mobile towers run on their own batteries for a few hours — a hotspot keeps essential work alive while your fixed line waits for the inverter.
Frequently asked questions
How long will a router run on a power bank?
A 20,000 mAh power bank (~74 Wh, about 50 Wh usable at conversion losses) runs a typical 10–15 W router + ONT for roughly 4–8 hours. Match the voltage exactly (5V/9V/12V) and use the correct barrel or USB-C cable.
Why is my fibre internet off when the Wi-Fi is on?
Your Wi-Fi router can be on battery while the ONT — the box that terminates the fibre line — has no power. Both boxes need backup power for internet to work during a cut.
Do mobile networks work during power cuts?
Towers have battery backup, typically a few hours, and get refuelled with generators in long outages. Speeds drop as everyone switches to mobile data, so a hotspot is a bridge, not a full substitute.