I have connected a UPS to my QNAP 469L via USB connection and I'd like to turn my PC off when the NAS detects the UPS is running on battery. The NAS, PC, and the switch are connected to the UPS "battery" outlet.
If you want it all running from the qnap I think you'll want master mode. Not sure what switch you have but does that really even need to be connected to UPS?
Having said that, and not having used networked UPS before, you'll need it UPS'ed to send the packets telling the PC to shutdown - presumably.