I powered the board from the PoE input. At the PoE output pins [point A] measured a solid 5 V.On GPIO pins 2 and 4 (VCC5V0_SYS)[point B], however, the voltage rose slowly over time from about 1 V to 4.5 V. When I connected a load to the 5 V power output [point B], the voltage never went above 0.8 V.The schematic is not available, so I traced the connection between the PoE output and GPIO pins 2 and 4. Between the PoE output [point A] and the GPIO 5 V pins [pointB] there are two SS34 diodes and several decoupling capacitors. The two diodes are connected in series with opposite polarity (one forward, one reverse). With a load connected, only residual voltage appears on that rail. That is expected: one diode is forward-biased and the other is reverse-biased, so they do not pass the load current.
Fix should be reverse orientation of second diode to forward. I could not check if it is manufacturer issue or design issue.