Ethernet quit working after Yosemite upgrade

DId you do a shutdown and then reboot?

Assuming that you've checked the connections, see below:

Intel-based Macs: Resetting the System Management Controller (SMC)

I have this issue too. After update to Yosemite ethernet works good. If I restart my Mac, ethernet stops working. I try reinstall Yosemite, but problem repeats. Ethernet works good until I restart my Mac. Resetting System Management Controller don't helped to me. How can I solve this issue?

I do have the same problem.

I have the same probleme. unable to connect with my ethernet cable.
If I connect the same cable to my other mac under Maverciks, there is no porbleme.

problem*.

For information:

iMac 27-inch Mid 2010

Please read this whole message before doing anything.

This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe modeand log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.

Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.

Remember that when you make changes to your ethernet settings you might need to do a shutdown vs a restart for the changes to take affect.

MY only experience with ethernet is using it with my two Mac DAW setup, using midi/audio And Vienna Ensemble Pro after upgrading to Mavericks. I had an issue getting ethernet to work and I solved my problem by going into to System Prefs>Network>Ethernet>Advanced and selecting Link-Local Only in the drop down menue next to Configure IPv6: and then shurting down both of my Macs and rebooting.

Maybe something like this will work.

I disconnected all peripherals, started to Safe mode, and had same problem. I deleted all of the login items. Restart safe mode, problem stay. Then I started usual mode. The problem persists, and then I went to the store. After I came back, suddenly Etnernet earned. I restart my Mac for test, and Ethernet again stopped working. I start Safe Mode and Ethernet works good. I restart Safe Mode, Ethernet again stopped working. I start usual mode, and Ethernet isn't working now. Very strange situation

I'm sorry for my terrible English

Thanks, but it did not help me

I have the same problem. No extra cards. I rebooted in safe mode. Problem still persists.

I disconnected all peripherals, started to Safe mode : the problem is still there.