Yes, that's listed as an ethernet error.
If you have an ethernet patch cable attached, try removing that from the computer, and run the test again. If you still get the failure, repair would mean replacing the logic board.
I ran the hardware test without the cable before I posted. I guess that's why I can't get connected to my router. I know there are several compatible USB to ethernet adapters that I can use, but is there a Firewire to ethernet adapter on the market?