The router or computer might be flipping between 100Mb and 1Gb. Since your NIC and router are both gigabit devices, the negotiated speed is initially 1Gb, but after too many errors they renegotiate at 100Mb. My guess anyway. I'd look at the NIC status right after a start up. If it's 1Gb, start a file transfer and see if it downgrades.
- Buy some new cables. CAT6 isn't all that expensive anymore, or in a pinch, short runs of CAT5e will do 80MB/s+.
- Manually set your NIC to 100Mb.
Last edited by Jizzler; Dec 21, 2012 at 05:15 PM.