Ethernet Not working

I had the same problem. It seems to be a silent security update gone wrong. Read more about it on Reddit:

https://www.reddit.com/r/apple/comments/47tfos/warning_software_update_03151913_ breaks_ethernet/

I just downloaded and installed OS X again and it solved the problem. Maybe not the fastest solution but a very easy one.

Thank you for this. I've been scratching my head all morning!

Apple seems to have released a fix.

Go to About This Mac > System Report > Software > Installations. Sort by Install Date and check to see if you haveIncompatible Kernel Extension Configuration Data version 3.28.2 installed. 3.28.1 is the version that caused problems.

If you haven't gotten 3.28.2 yet, try going into terminal and typing:

sudo softwareupdate --background

Enter your password when prompted. Should update in a bit. Keep checking System Report until you get it. Reboot and all should be well.

Great..... this has fixed it for me. Thanks for this.

Nicky

I had the same problem this morning after booting my computer. Also, I received an error message whenever I tried to login to my Application account. Seems that the two are related. I spent about 30 minutes on the phone with Apple support trying to resolve the issue. They could not resolve the problem, so I took my computer to the local Apple store this afternoon. After some research, the technician at the Apple store provided the following explanation:

Apple pushed out a security patch last night and this morning which as part of the patching procedure, they turned off the ethernet service, but the patch software had a bug resulting in not turning the ethernet service back on. Hence, if you are connected to the internet via ethernet, you will get a message that the ethernet cable is disconnected and also if you try to login to you Application account you will receive a failure message stating that your computer is not recognized. According the Apple tech, a fix is in the works, but no time schedule for it being deployed.

The explanation sounds plausible. However, I'm somewhat perplexed that Apple phone support was not aware of the issue.

For now, I was advised to connect to the internet via WiFi if I have the capability, which I do.

Hope this provides some insight into the issue.

The following is from a Reddit link (https://www.reddit.com/r/apple/comments/47tfos/warning_software_update_03151913_ breaks_ethernet/) and from IdownloadBlog (http://www.idownloadblog.com/2016/02/27/security-update-disables-ethernet-on-som e-macs/). They are posted as screenshots as sites like these in the future may invariably have their posts downvoted/blogged into un-searchable oblivion.

Thank you dude. it works

Apple are aware. Read this:

If the Ethernet connection on your Mac stopped working recently - Apple Support

Follow-up to previous post above. It seems Apple was on this all along and another silent update may have been applied to reverse the blacklisting of the native Broadcom driver for the iMac ethernet NIC. Without doing anything other than having left the computer on and connected to the internet, ethernet connectivity (cable was never unplugged) came back online. Fields of view changed and updated automatically without doing anything (progression shown from late pm PST 2/27/16 to early am PST 2/28/16). So, snafu seems fixed as sudo terminal commands were not used as suggested by some of the other post for a fix/workaround. Apple offers help in related article "if your ethernet connection on your Mac stopped working recently" at the following link in case there are others not as fortunate to have it updated automatically:

If the Ethernet connection on your Mac stopped working recently - Apple Support

Follow this link to the fix. Thank you! Thank you! Thank you.

I was checking cables, router, etc. for a day. Calling Charter, etc. This fixed it!