I've been using Sierra since beta and ever since I first upgraded, the built in ethernet port has not worked - it shows up in network preference but always says the status is "cable unplugged." I tried removing all the network interfaces, rebooting, and adding them, back, but still it's not working. Any suggestions would be appreciated.
MacBook Pro, macOS Sierra (10.12), null
Reset the System Management Controller (SMC) on your Mac
If the ethernet port still shows as unplugged, let's test with another good known ethernet cable to verify it's the Mac and not the cable that's causing the issue.
Best wishes.
OK, I did the SMC reset (twice). I also unplugged an ethernet cable connected to another Mac, with a good connection, and plugged it into the problem Mac. It still did not recognize that a cable was plugged in. Thanks.
I have the same MBP with macOS Sierra installed.
My ethernet port works fine.
However I did have problems with my ports before.
Solution was to clean out all the dust in my ports that was causing a bad connection.
I used a can of compressed air that I purchased at Walmart.
https://www.walmart.com/ip/Dust-Off-Electronics-Duster/25596750
Give it a try.
Ethernet port on macbook pro (mid 2012) not working after upgrade
