Cannot share my internet connection via Wi-Fi from my Mac I am using El Capitan 10.11.2.

I go to sharing and select 'Display Ethernet' in the Share your connection from menu. The display ethernet port is the port with the ethernet cable leading to the internet.

I check 'Wi-Fi' from the To computers using: list and turn on Internet Sharing.

From another device, I do see the Wi-Fi network created by my Mac show up and I can try to connect to it, but the connection never succeeds. 

I think some preference file somewhere has become corrupt because I can do this same thing using another machine without any trouble and I wanted to avoid wiping the problematic machine and starting from scratch if I can avoid it.

The only clue I have are messages in the console log:


  1/7/16 3:56:11.733 PM bootpd[695]: DHCP DISCOVER [bridge100]: 1,c8:6f:1d:15:8c:80 (ericss-iPhone)
I was desperate to get internet sharing going on my mac as, at the moment, it is my only router. It was going fine and suddenly stopped, and I hadn't updated recently. I ran the WirelessDiagnostic tool after doing a bit of searching, and that made the internet shareable again. It's an app--not a setting; I mention this because I wasted a lot of time trying to find it in System Preferences.