Well, of course that is in the man page of ethtool. But basicaly you are right, allthough in my 13.1 it says:
which is, strange enough, different from what you have.
Supports Wake-on: g
In any case, that is what I wanted to check. In my case, it won't work, because while the NIC does support it, the system (BIOS) doesn't. In your case, you say it worked earlier, thus I assume that hardware and firmware are supporting this.
BTW I have tested it here on another system (wake from my router) and that worked, thus nasicaly 13.1 is able to do this.
But at the moment I am out of ideas. Hope others tune in.