Fellowes UPS Model 500VA UPS (99066)

It's pretty easy to test - connect up the USB port to the NAS, leaving the NAS power alone. Put a reasonably similar power load on the UPS (a lamp perhaps), and disconnect the UPS from the main power.

After a bit, you should see the NAS shut down [when it receives the power-critical event over USB]. Check to see that the lamp is still powered.

Then recharge the UPS, and connect the NAS to it instead of the wall power. Try unpowering the UPS briefly, and then check to see that the NAS is still working correctly.

Or is the real issue here that it doesn't work?

The NAS has the ability to talk to APC UPSs and determine when UPS power is low on power to facilitate a safe shutdown. I cannot find any documentation stating that the same functionally is available with the Fellowes UPS Model 500VA UPS instead of an APC UPS. I am attempting to determine if anyone knows if it will work. I can test it however I was hoping to determine if someone already tested.

Thank you for the insight - The NAS is plugged into the Fellowes UPS and working. I am looking for the smart features to work as well.

Well, I gave you an easy way to safely tell if the UPS monitoring in the NAS is working correctly with the Fellowes. If I were in your position I would use it. Several folks here have reported data loss related to power issues.

In addition you can see the UPS monitoring status in Frontivew. But that doesn't give you full assurance that the NAS will shut down before the battery runs out. The test I outlined can tell you that w/o any risk to the NAS data (since the NAS remains fully powered throughout the UPS test).

Makes sense. Thank you... :O)