Why did OSX 10.9.4 Internet Sharing stop working? I had Internet Sharing working correctly on my iMac with OS X 10.9.4. I was sharing my connection from ethernet to computers using Wi-Fi.

After I rebooted, my iPhone can connect to the Wi-Fi connection from the iMac OK, however has no internet access. I can access the iMac's local server pages, but not google.com etc.

I have rebooted numerous times. What can I do to fix this issue?

I am behind a cooperate proxy which settings are set correctly.
The best option here is to speak to your employer's technical support people.

If their policies permit the sharing of the wired corporate network to wireless devices they should assist you in setting up the connection or at least point you in the right direction.

If they do not, then it is probably best not to breach their policies.