Does anyone know whether the PoE output on the RB5009UPr+S+IN is galvanically isolated? I believe this is optional in the PoE specs, but I've run into issues before when it's not isolated.
I had a TP-Link PoE switch years ago that ran off a -48VDC power supply, and it connected the -48V rail to GND, and the 0V rail to +PoE, to make it look like PoE was being supplied at +48V. Because the switch power supply connected 0V to earth, it meant any PoE powered device had its GND sitting at -48V referenced to the switch PSU, and every other device had its GND at 0V referenced to the switch PSU. So if you tried to connect, for example, a PoE-powered Raspberry Pi to an LCD monitor, as soon as you plugged in the HDMI cable and the two different GND connections came together, you'd short out the switch power supply and the whole switch would lose power. I managed to solve the problem at the time by adding a 5V DC-DC converter between the PoE splitter and the Pi, which didn't change the voltage but provided isolation. Later, I switched to a second-hand Cisco switch which no longer needed the DC-DC converter as it had isolated PoE output.
So I'm wondering whether the RB5009UPr+S+IN electrically isolates its PoE output from the input supply, to avoid issues like this. Does anyone know?
On a related note, are the multiple power inputs isolated, or are, for example, all the negative supply inputs connected together internally?