I got this from a colleague of mine.
"When one link partner is configured for "auto-Detect" that only means that the speed is autodetected. Duplex can not be autodetected. Our User documentation states that our device should have speed/duplex configured to be the same as the link partner. So either both link partners configured for "Auto-Detect", or both link partners forced to the same speed/duplex setting.
Please see the Intel® Gigabit Desktop Adapter Guide, Setup Speed and Duplex section on the Release 16.5 CD for more detail.
Let me know if this helps.