To choose the right UPS, check your router's power adaptor for the necessary information, then buy an affordable option ...

so they set about whipping up a backup power solution to keep their Verizon ONT fiber modem up and running in such events. The I-211M-L modem is actually equipped to run on backup battery power ...

It's connected to the Xfinity 10G network. When the power goes out, the router's mesh system has a backup cellular connection with unlimited cellular data and a four-hour backup battery.