I had no idea there are so many on the market. Most lay claim to keeping power to your computer in a power failure long enough to save your data and shutdown.
But all I want is to power my comcast modem for an hour or two. During the recent house power loss [xformer blew up in front of my house] my computer noted I still had four hours of battery life. But with out the comcast modem, that’s useless.
Any company rec’s? I’ve heard APC is good. Yes/no ?
I am an electrical contractor I have been doing commercial work since the early 1990s. Most of the units I have seen being used are APC, CyberPower, and Tripp Lite. We have, on occasion, had to replace the batteries or the complete units. I have not noticed any issues from any of those three.
You might want to consider getting in touch with the technical support department of any of those three companies. They would probably be willing to go over what you are looking for and recommend what they feel would best suit you.
UPS may not be the answer you are looking for. I have a portable Honda generator for power outages. I can run a refrigerator, lights and electronic equipment. I find my internet is always out during power outages even when I power up the modem/router. Something upstream from me also needs power and that is always also out. I use the mobile hotspot on my phone to get on the internet during these occurrences. But your situation may be different and may be different depending on how widespread the power outage is.
@robertpri if your objective is to continue internet, why couldn’t you switch to using your phone as a hotspot during the outage ?
Here’s an alternative to comcast, it’s cheaper and doesn’t require electricity. During the pandemic, in the winter months, we spent lots of time working puzzles and reading to avoid on-line saturation.
UPS’s are fine for short outages and to protect certain equipment from power spikes and surges.
Personally I have multiple small UPSs in the house. They protect my desktop computers, expensive TV’s and so on. One supplies power to he on-demand propane water heater. It needs 120 volts AC to power the igniter and if you are taking a shower and the power fails the water turns cold instantly! Thus, in the off chance, I have elctric for that igniter and can still enjoy hot water.
Don’t expect a UPS to power things for long. It will depend upon how much power the items plugged in require. I have a heavy duty printer and computer on a UPS. If power fails when I am home, I will power down the printer immedietly and start to finish up work on the computer and manually shut that down later.
With Internet you would need to keep power on for both the modem and the separate router, if you have one. You might get 1/2 hour or less time depending upon your computer draw. Also, you might consider an LED bulb on that same circuit to reduce power draw.
I have lately purchased UPSs at Costco in the $100 range. The internal batteries will fail after a couple years. Those batteries are fairly easy to replace, even for a neophyte. The batteries are generally the same ones used for electric gate openers and I can buy them at Home Depot. I also have bought a pack of them on Amazon at a tremendous savings.
Another drawback to power outages and Internet is this: If your neighborhood is out of power, the amplifiers for Internet may be out also. Here in our rural area, someone will take out a telephone pole and Internet, Phone and power all go out (your mileage may differ). Because of logistics here, a single pole out may mean hundreds of us are without those utilities for 6 hours or more. The replacement poles are kept an hour or two drive away. Then they have to dig in rock to set a new pole. Fun Times!
If you are only concerned about your inhouse connections like backing up data from a computer to a local NAS network connected disk drive, or you have a local drive with video/audio and want to keep that running, then you may be fine. I personally have lots of content on a locally connected computer that I can stream from.
A side note. When I worked at an office there was a personal UPS under the secretarys desk. She complained that it didn’t keep anything running during a power failure in the building. I discovered why. Like many UPSs it had two sets of outlest, some were on the UPS itself and supplied emergency power while the others just supplied surge protection. Her computer and monitor were on the surge protection side but on the UPS side and during a power outage, she would be able to sharpen all the pencils she wanted! 
Wow, thanks guys…! Great comments and ideas…
This is why I love the CH forum. So much experience and expertise.
I forgot to mention… before I got a cellphone that had a hotspot link, I used a program called PDANET from a company called June Fabrics (I know, HUH?) June Fabrics PDA Technology Group
It created a hotspot so to speak for my cellphone. It used the charging port to connect to a USB port on mydesktop computer. I used my cellphone dataplan to access the internet on my desktop through that cable. I had lost my internet connection for a few days due to a storm but was able to use the desktop and my cellphone to browse the internet, receive mail and yes, even download Windows updates.
From June Fabrics?..SEW FUNNY!.. 
I have three APC’s and indeed it has enough power to let me shutdown the computers. I also bought an Ecoflow Delta 2 battery to keep the refrigerator running for 6-7 hours. We have frequent enough outages to make it worthwhile. Check HD for sale price. That said it IS a bit pricey but so is restocking the fridge!
They have smaller units too.
We lived in a houseboat in the Cal Delta a few years in the early 80’s. Friend was an EE and installed a bank of lead-acid train batteries connected to an invertor that powered the entire boat for many hours.
But not the fridge. We powered up the aux generator 2-3 times a day for the fridge. Since fuel was precious and fuel docks often miles away, we created a firm schedule how many times a day we could open the door.
Houseboat living was a lot of fun, but could not do it now…!!!
I know, cuz this THREAD has me in STITCHES. I will ZIP it for now because my off the CUFF remarks may make me SOCK someone who NEEDLEd me and then I’ll get the BOOT.
I understand, I’m cut from the same CLOTH. 
In my instance, there is no cell phone signal within 2 miles of my house. I cannot even make calls because everything is long distance and for that I use Google Voice or wifi.