This Compact Device Keeps Small Electronics Running On | Gizmodo
From the horse’s mouth
An uninterruptable power supply that I have previously recommended for use with routers, modems and the like was the APC Back-UPS ES series of UPS devices. This was typically for households who live in areas where the power supply may not be stable and they end up having to reset the equipment at the network’s edge in a certain manner every time the power goes down.
Now APC have issued a new and cheap UPS device specifically targeted at modems, routers, VoIP ATAs and the like in the form of the Back-UPS Connect 70. This 75-watt / 125 VA device is sold for US$50 and has enough power to service laptops or these other devices. You could even think of running more of these devices to allow you to support different loads such as one servicing a router, modem and VoIP ATA and another one servicing one or two consumer-tier NAS units.
At the moment, it is only available as a 120V unit for the North-American market, but personally I would like to see the arrival of a 240V unit targeted at the European market at least. This is more so with the French market where the Freebox and similar “n-boxes” are there to provide telephony and Internet service and are dependent on a reliable mains supply.