Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a thunderbolt to ethernet cable on a MacBookPro Retina on Lion.

Sometimes the thunderbolt to ethernet connection does not work. It seems to occur when I switch network locations (e.g., I move from my home network to my work network). Restarting the computer fixes the problem, however, I don't want to have to restart my computer.

How can I force thunderbolt to ethernet to connect without restarting the computer?

More details:

Under network settings, there is a red dot and not connected on "Thund...thernet". It further says:

Status: Cable Unplugged
Either the cable for Thunderbolt Ethernet is 
not plugged in or the device at the other end 
is not responding.

Under system information - thunderbolt it states

Thunderbolt to Gigabit Ethernet Adapter:

  Vendor Name:  Apple, Inc.
  Device Name:  Thunderbolt to Gigabit Ethernet Adapter
  Vendor ID:    0x1
  Device ID:    0x8003
  Device Revision:  0x1
  Route String: 3
  Firmware Version: 5.5
  Status:   Connected
  Link Status:  2
  Port Micro Firmware Version:  0.0.8

Under Network - Thunderbolt Ethernet it states:

Thunderbolt Ethernet:

  Type: Ethernet
  Hardware: Ethernet
  BSD Device Name:  en1
  Configuration Method: DHCP
  Configuration Method: Automatic
  Exceptions List:  *.local, 169.254/16
  FTP Passive Mode: Yes
  Service Order:    0
share|improve this question

I had this problem, too, and an Apple Support call and Genius Bar visit later, I had the answer: if you're using Network Locations that preexist your Thunderbolt display, it doesn't seem to auto-add the possibility of "Display Ethernet" to your available network ports. To solve this, either:

Create a new Location in your Network system preferences. It will finally detect the "Display Ethernet" and use it. It'll slowly change from disconnected to No IP to green-is-for-go.


Fix an existing Location by clicking the + to add a port and choosing Display Ethernet. It'll slowly change from disconnected to No IP to green-is-for-go.

share|improve this answer

It seems like this issue at least for me may have had nothing to do with the thunderbolt connection. Rather it was a more mundane networking issue. I.e., when I moved between networks, network settings needed to be reconfigured. Techniques like renewing DHCP lease and using the "assist me" procedure in network preferences seemed to be sufficient for me to reconnect using Ethernet after switching networks.

share|improve this answer

Workaround that worked a few times for me:

  • unplug the thunderbolt converter
  • Wait few secs, ten plug it back in
  • Go to Settings/Network/advanced/refresh DHCP lease
share|improve this answer
Hitting the "Renew DHCP Lease" button in the advanced settings -> TCP/IP of my adapter solved my problem. Thanks for sharing this solution! – KyleFarris Jun 23 '15 at 1:27

Same problem here. IMHO it's a bug in OSX. Unplugging/plugging kicks something in the OS and then it comes back to live.

share|improve this answer
This does not really answer the question. If you have a different question, you can ask it by clicking Ask Question. You can also add a bounty to draw more attention to this question once you have enough reputation. – jherran Apr 21 '15 at 18:27

Same problem in Yosemite on a MacBook Pro with two Thunderbolt ports. Mac OS X seems to believe that the Thunderbolt ethernet adapter is really another Thunderbolt bridge because I see two Thunderbolt bridges. The solutions suggested are vague and clumsy, but lacking a command line solution there is only unplugging (like above), replugging, then adding an ethernet to an existing location without the wifi adapter in it.

The actual problem seems to be caused by a wifi connection becoming active and precluding the ethernet connection. The best and most permanent fix I have found is to turn off wifi before arriving at the office. Then plugging in the ethernet always works. But if I allow that wifi connection to become active first, then plugging in the ethernet quite often fails.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.