Wifi and Ethernet not working after Yosemite upgrade

My wife installed Yosemite on her Intel iMac last night. At the time it was working without issue. Today, the computer shows that wifi is connected and ethernet is connected, but it won't connect to the internet. Other devices that are connected to the router have no problem accessing the internet. If you run Diagnostics, it says that there is an internet connection, but mail, safari, firefox, won't connect.

Is anyone else experiencing this?

The computer in question is a:

IMac (27-inch, Late 2013)

3.2 GHz Intel Core i5

16 GB 1600 DDR3

iMac, OS X Yosemite (10.10)

Posted on Oct 17, 2014 11:55 AM

33 replies

Apr 6, 2015 11:09 PM in response to ettocs

Hi, I aslo have the same problem,

But after got assistance, I was able to fix the Ethernet connection problem.

Go to System preferences and Click Network,

Then select the Ethernet service and click on Assist me...

Then click continue in Network Setup Assistant.

Then select "I use a cable modem to connect to the internet" or "I connect to my local area network (LAN)"

from the list and click continue.

After that I was able to fix the problem.

Thanks.

Oct 25, 2015 6:29 AM in response to ziarn

Rebooted and moved wi-fi to top of list. Worked immediately.

LOL_V

Level 1

8 points

Nov 23, 2015 12:29 PM in response to FtechUPgrades

Renew DHCP Lease did it for me when the cable co upgraded the modem and I could not for the life of me connect via ethernet. Wifi? Sure. Ethernet, DENIED. So I renewed the DHCP lease and now we're back in business.

Thanks!

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Wifi and Ethernet not working after Yosemite upgrade