In the event of a power outage I'd like to keep my Internet running. I've been told that cable typically stays up when power goes down so, my question is, how do I determine how long a UPS will keep my modem and router up and running?
As with anything that has batteries, it depends on the load your modem and router draw as well as the capacity of the battery in the ups.
However, it's got to be said that UPSs are primarily designed to give you time to safely shutdown your computer (2-3 minutes) and unless you're on a laptop with a good battery you won't actually be able to use the internet if your power goes down.
I know it depends on the load, I'm just looking for a ballpark. I'm not seeing how many watts a Motorola SB6120 SURFboard DOCSIS 3.0 pulls on their website.