Q: Wifi and Ethernet not working after Yosemite upgrade

The likes don't seem to work.

Same problem with my Mac Pro Mid 2010 on both ethernet ports.  Truing port off then back on fixes the problem for a short period of time, usually less than a day.

I did a restore of Yosemite and it had no effect.

WiFi is working, thank goodness, otherwise the computer would be worthless.

This needs to be fixed sooner rather than latter.

So spent 6 hours yesterday doing everything on the sugested posts.  Finaly at 01:00  went to system preferences/ Network,   unlocked the panel and deleted both the ethernet and wi-fi connections in the panel. (using the minus button)
Saved rebooted and when restarted went back and created a new conection .  has been working perfectly ever since.  Cant find original person who posted it as I was so tired,  but thank you anyway.

Felt like as was back in the microsoft world for a while there!

Hello, any news about how to solve this problem?

I updated to Yosemite few days ago, and ethernet connection doesn't work. wifi is ok instead.

I have a Macbook Pro, and I've already tried what suggested in this post, but no way!

Thanks in advance

After upgrading to Yosemite on my 27" iMac whenever I rebooted I would initially have no Ethernet or wifi internet connection. It always eventually started working, but apps like Dropbox Twitter Adobe cloud would time out and I'd need to quit them and relaunch even after the Internet connection started working. Resetting SMC seems to have fixed the problem of the (very slow) Internet connection. Thanks for the tip!

Had the same issue when I updated both laptops to Yosemite - wouldn't connect to my wifi network and kept getting an error asking me to run diagnostics. 

what I did:

1. Open network preferences - press advanced

2. Delete wifi router name

3. click + sign to add another network

4. press show networks

5. select your router

6. enter password.

this worked for both laptops - hope that helps

I confirm cshewry method, a few posts before for Ethernet access at least :

- clear all connections in Preferences/Network via ' - '

- reboot

- set again the Ethernet connection

On my side, I have an iMac 21,5", mid-20011 coupled with a 1Gbps broadband internet access, and since the upgrade to Yosemite the internet access was slower, sometimes objects were missing in the webpages. A speedtest was giving me 660 Mbps instead of 840Mbps expected. After the operation described above, I jumped to 940Mbps.

Clearly, something is wrong in the Ethernet setting after the upgrade to Yosemite.

Hope this helps too.

8.1.1 work for 8 days before Ethernet ports stopped again.  Tired removing and adding back in the ports, if that is all it takes that would be fantastic.

What fixed mine was to restore to original system image, which was Mountain Lion. Then upgrade to Yosemite from there. I had a couple of hiccups, once I reset the DNS lease I haven't had any issues. I was not thrilled about having to spend my time doing this.

Hope others don't have the headache.

So annoying! Apple has been around since 1976. You'd think that after nearly 40 years, they'd stop mislabeling their beta version operating systems!

I had this same issue, here is what I did.  Go to the System Preferences and delete the Ethernet device.  Then add a new Ethernet device.  Restart the machine.  All worked fine.

Hey thank cshewry - that solution worked for me too - I have one of those new 'trashcan' looking mac pros and I was really surprised that it would Crawl and I mean Crawl when connected via either of the Ethernet ports - only wifi would work.  I was really frustrated with this - took your easy steps of deleting ethernets/wireless and restarting and putting them back in and its working like a champ again - thanks!  Just confirming worked for me.

Thank you very much. This seems to work for me too!

This worked for me!!!!thanks

Deleting and reinstalling an ethernet network only worked temporarily for me. Best solution (I received this solution from Apple Support) is to create a new location in your Network (top of Network box in System Preferences). After I added a new location (default was "Automatic") I have not had any issues with internet connectivity.