rb1100ahx2 PoE in voltage and amperage

Hi
I have rb1100 ah x2
https://routerboard.com/rb1100ahx2
It was connected with power cable from UPS1 and POE from UPS2. today we experienced electric problem and when first UPS failed POE in did not worked. when I checked the green LED on POE it was blinking slowly like alarm.
I think my POE (Original POE of ubiquiti output DC 15V - 0.8A) was not strong but I cant found which voltage and amperage is good for this device
Can I use 24 volt POE with 2.0 A (amperage)? or I should get 12 volt 1.0A? Or will hurt the device using poe with higher voltage like 48 volt?

Supported input voltage 10 V - 28 V
Anyway best to use over 12v. Power, at least 20W
https://routerboard.com/rb1100ahx2
Where did you searched? Did you search?

of course I searched.
In spec link there is nothing about amperage.
there is many type of POE 12V 1.0A, 12V 1.5A, 24V 1.0A, 24V 2.0 A ???

I = W / V
So 1.6A = 20W / 12V
Or 0.83A = 20W / 24V

In the other direction
W = V x I
12W = 15V x 0.8A
Which is under spec (20W according to InoX)

My RB1100ahx2 has 15w in idle, so a minimum 20W is preferred.