Mountain Lion Ethernet Problems? Check Internet Sharing System Preferences

I have been having a mess of a time with multihoming on my 2011 Apple MacBook Pro since I have moved to Mountain Lion (10.8.x) and found all sorts of others in the Apple Support Forums with wake from sleep ethernet issues and other similar problems. The ethernet port recognizes there is connectivity but doesn’t accept a DHCP address.

I was right about to rip-out all my network-related .plists in /Library/Preferences/SystemConfiguration when I thought that it might be getting confused with DHCP if I have turned-on Internet Sharing in the Sharing Control Panel. Sure enough, I had it on for some reason doing some network work a few weeks ago and that was the source of the issue.

After disabling that, I was able to multihome again without a problem.


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  • Thank you Jonathan, a million for giving me the solution to this pesky problem. I found this site by mistake as I was deep into trying finding a Unix solution – and was googling the command internetsharing.. On the bright side I must say I learned a lot of different network commands and routing in Unix. I was actually only minutes away from installing the system again – and would not have been any wiser to the real problem.

    • Kenneth,

      Really nice of you to take the time and post a comment. This drove me nuts, so when I found it, I just wanted to put it out there to maybe have someone else not go through the madness. Glad it helped!

      Take care and thanks again for posting…