When they don't work I either change the motherboard or install a network card.
Recently I purchased an ASRock Z97, Intel i5 4690K, and a R9 390 (irrelevant). I had no issues during installation or setup. The problem occurs with the motherboard Killer e2200 Gigabit ethernet port. I had looked and looked and looked for solutions, but they ultimately lead to more problems or questions. Here are my steps taken so far:
1.) Updating ethernet connector drivers from ASRock website
2.) Downloading software from ASRock motherboard disc, ultimately limits my original External Networking card, so I uninstall Qualcomm Atheros as this limits my wireless connection.
3.) Ensuring that onboard LAN is enabled
4.) Checked integrity of cable, works on other devices
5.) Enabled DCHP
6.) Assigned various or random variables for both IPv6 and IPv4
7.) Disabled, left for a bit then Enabled
8.) Disconnected power, left for a bit, reconnect power
9.) Assigned and changed the network types for it "Public, Work, Private, etc."
10.) Flipped a table
I might've missed a step or two throughout the process, but I have tried nearly every online google search solution there was and I still cannot find a solution... P.S. when I do not update my Ethernet driver, local area connection is not even an option under "Network and Sharing Center".