we have a p2 with ethernet controller board and like to be able to save power and turn ethernet off if not used. i see no power difference whether Ethernet.on() or Ethernet.off()? does Ethernet.off() actually ment to keep the controller in reset or put it on low power mode?
I have not attempted it, but it looks like the W5500 can use power down by setting the OPMDC bits in the PHYCFGR register by SPI. However even when powered down it uses 13 mA, so if you need really low power you'd probably need to add a way to externally power it down.