I put an oversized UPS with extended battery pack on my network gear (Cable modem, Router, ethernet switch and Wifi nodes) to give me almost 8 hours of runtime in a power outage. I've found, however, that the cable company's UPS only lasts around 6 hours since that's how long it takes for the internet to go out and the cable modem to lose carrier.
In the winter months (when we have most of our power outages), I pay for a pre-paid cellular SIM for backup. The cell tower(s) that serves my area must be on generator, it doesn't seem to go down even in long power outages.
That makes sense, network gear doesn't suck a lot of power. For compute though, I always have to have the conversation with clients that multiple hours of UPS backup for a server rack is crazy expensive. They are usually better off with a UPS that can take over while a generator spins up if they really need that kind of reliability. I always ask, what are the odds that your 8 hour power outage scenario isn't from something catastrophic like a flood or a fire, eg, if the power is out for that long, something is probably literally on fire and you've got bigger problems.
In the winter months (when we have most of our power outages), I pay for a pre-paid cellular SIM for backup. The cell tower(s) that serves my area must be on generator, it doesn't seem to go down even in long power outages.