I just flashed the latest 21.02 snapshot (r15860-a75520c678) on a brand new Edgerouter X. The wiki says to enable PoE passthrough by putting the following code into /etc/config/network:
config gpio_switch 'poe_passthrough' option name 'PoE Passthrough' option gpio_pin '480' option value '1'
However that did not work for me. I made sure the gpio_switch service was enabled and I rebooted but I couldn't get it to work. Adding the following to the custom startup script does work however:
echo 480 > /sys/class/gpio/export echo out > /sys/class/gpio/gpio480/direction echo 1 > /sys/class/gpio/gpio480/value
So I don't know if this is a bug in the snapshot version of gpio_switch, but either way it might be helpful to add the second method to the wiki just in case the first doesn't work.