I was using a small box as a router and one of the ports started going off and coming back at 100M. I truly believe it is simply that it was a case of overheating. Although CPUtemps were only about 67 degrees, the physical box itself was almost burning hot. Isolved the cooling issue and never had the issue again. Jul 28 15:09:27 swithbox kernel: e1000e: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx Jul 28 15:09:28 swithbox kernel:........