On my Mac Pro 5,1 I cannot get it to connect via the ethernet port. I am running high sierra, The cable works fine, has a constant connection on my macbook pro. I have tried Reset PVRAM Reset SMC Delete Network System Preferences Reset Router When the ethernet cable is plugged in it says unplugged, connects for about .5 seconds than goes back to saying nothing plugged in. I have tried both ports and its the same result. Anything else to try?