Are there any LEDs lit near the Ethernet connector on back of the PC?
Did you look in BIOS setup (reboot and immediately press F2) to make sure the onboard NIC is still Enabled?
Is the NIC still listed in Device Manager or did it disappear? Are there any "unknown" devices listed in Device Manager?
Have you tried uninstalling the NIC driver then reinstalling/updating the Intel chipset and AMT HECI drivers, rebooting and then install the NIC driver again? Unless the chipsets are correctly installed, other drivers may not install or may not work.
There's a new thread in the XPS forum about a similar issue with the XPS 8700, but that one is running Win 7, so it may or not be the same problem...
Forum Member since 2004
I am not a Dell employee