Found out something interesting today. My NanoStation Loco M5 (it's am XW version) will run on a little over 5v via POE. Dropping it just a hair below 5v would allow it to start but it couldn't run the wifi module. I suspect 5v may not be stable in the long run. That's a test for another day.
My UAP-AC-MESH, which takes 24v/48v needed a full 24v to run. Even 16v wasn't enough. I didn't try anything in the 16v to 23v range.