Had an impromptu test of the home theater system's UPS last night courtesy of a neighborhood power outage. What with having our office, comms, and home theater stuff on UPSs, I figured you bozos would like the data as a real-world reference.
Home Theater System Components
LG 65" NanoCell 90 TV (model 65NANO90UNA)
Yamaha RS-A1080 receiver
XBox Series X
Panasonic blu-ray player (model DP-UB820-K)
D-Link 8 port switch
ASUS 1900 wifi router.
Small USB fan
UPS
APC BX1500M (the no-frills 1500VA unit)
Results
All HT components were plugged in but powered off. The router and network switch remained active. In this configuration, the UPS indicated 241 minutes runtime. I figure there will be some amount of error, so call it 220 just for the headroom. Powering on the TV and receiver as a test, runtime dropped to 75 minutes.
Our office setup is also on a 1500VA UPS. With everything powered off except the UVerse modem/gateway and an ASUS 1900 router, indicated runtime was 267 minutes (allowing around 240 to account for error). UVerse comes in on self-powered legacy copper so our internet access remained active during the outage.
Conclusion
With everything powered down except the network gear, we have four solid hours of internet/comms with both routers running. If I expected the outage to run longer, I could pull the downstairs UPS right away and keep it as a power reserve for the upstairs UPS. I might even be able to daisy-chain them so the failover is automatic (never tried, but it's an interesting scenario). That gives a solid 7+ hours comms on UPS power. Should the outage be accompanied by generator failure or I have to drive a ways for extra generator fuel, that's a nice safety margin. It's also enough time to semi-mothball the house and make alternate domicile arrangements if things have gone completely pear-shaped. In that event I'd throw both in the truck as last-resort portable emergency power. I can recharge them from the truck's 110 outlet.
Brad