How to keep your broadband router on in a power cut (UK)

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Option one: keep the router powered

A router uses very little, typically 8 to 12 watts. Look at the label on its power supply. Most say something like “Output: 12V 1.5A”.

On full fibre you have two boxes. The router, and the small white box on the wall where the fibre comes in. Both need power or nothing works. People forget the white box. I did, and I’d drawn a diagram.

Three ways to do it, by cost:

A mini UPS such as the Eaton 3S Mini. It sits between the plug and the router, and takes over the instant the mains drops. Nothing to remember. This is the one for most people.
A power bank and a step-up cable. A USB to 12V router cable lets a power bank run a router. Check the voltage and plug size match your router, and test it on a calm afternoon. A 20,000mAh bank runs a 10-watt router for about six hours.
A power station with the router’s normal plug in it. A 256Wh one runs the router and fibre box for the best part of a day.

Option two: a second way online

If the fault takes out the broadband too, you want something that doesn’t use your line at all. A battery-powered 4G MiFi with a SIM on a different network from your phone costs about the same as a decent torch.

Option three: your phone

Every smartphone can share its data as a wifi hotspot. It’s free and you already own it. It also flattens the phone in a few hours, so it needs a power bank beside it.

The catch with all three

In a big, wide-area cut, the mobile masts and street cabinets are on batteries too, and those run out. Some last hours, some much less. Your backup will ride through the common kind of cut, which is local and short. For the rare big one, the answer is an FM radio and a paper list of phone numbers.

Digital landlines

If your home phone plugs into the router, it’s a digital landline and it stops when the router does. If you rely on it, because of poor mobile signal, a telecare alarm, or just because you do, your provider has to offer you a way to reach 999 for at least an hour in a power cut. That’s usually a free battery unit. Ring and ask. They are obliged to help and somewhat less obliged to mention it.