I'm powering my RPi (rev 2, model B) through GPIO pins - same connection like here - using it ethernet is not working, though the ethernet works fine when powered through the microUSB port.
The problem seems to be some kind of under-voltage in Ethernet connector. I saw this happens to some people with USB, and the solution is simple - solder a connection between GPIO and USB directly.
But I can't find any solution for ethernet - could there be one similar to the one for USB? The Pi's schematics are too difficult for me to read.
So, what to do? (to power it with microUSB is NOT a solution for me)