I have the same problems using debian linux image. Sometimes it turns on, but mostly not, at least if the cable is longer. I also use Cat6 (PremiumCord) cables. Somehow I had no problem at my office, where the cables run a long way from the switch. I suppose the cables are Cat5 there. Is this some hardware issue?
I just bought a new 10 meters cable to run the pine in the next room and now I am pretty puzzled... it does not work, mostly. Even reconnecting to a shorter cable does not activate the port. I have to power the Pine off, connect a short cable and power on. When the port activates, I can reconnect to the longer cable again, but that would be not of much help if I really moved the Pine further away...
I just bought a new 10 meters cable to run the pine in the next room and now I am pretty puzzled... it does not work, mostly. Even reconnecting to a shorter cable does not activate the port. I have to power the Pine off, connect a short cable and power on. When the port activates, I can reconnect to the longer cable again, but that would be not of much help if I really moved the Pine further away...