I went
here. Notice there is a BIOS update Version 2601 from July, I definitely recommend that, but it doesn't mention it is a fix for ethernet connection, just possible video issues.
I couldn't see a LAN driver so maybe more info ...
Could you download and install
SIW. Then run it.
Under Hardware ... PCI ... Find Ethernet in the list
I believe you will find something like PCIe Gigabit LAN driver but I need some Maker & #s or something to find the right driver
Clifford or TorrentG, do you know what would be the correct LAN driver for this mobo?