My Mac insists on connecting to my neighbors Comcast/XFINITY WiFi rather than my home wifi. The usual recommendations didn’t work. (Note, if you don’t run as admin, and want to play with WiFi settings, you need to first click the unlock icon on the Network Preference Pane before you click “Advanced”. Bad UI.)
Despite deleting XFINITY from preferred networks I could still immediately join my neighbors network. Sierra didn’t seem to honor the order of WiFi networks I’d set. I searched Keychain but couldn’t find Comcast or XFINITY left anywhere.
The new trick to look to see if you have a Profiles PreferencePane. There, if you’re like me, you’ll find a “User Profile” called XFINITY WiFi. (I dimly recall installing per XFINITY directions, but now they advise us to use an app — I think the app may allow one to prioritize a local WiFi).
My XFINITY WiFi Profile description said “Automatically connect to XFINITY WiFi hotspots”. It had an Enterprise Profile ID and I suspect MacOS is prioritizing it. So I deleted it.
And … I still connect to the XFINITY WiFI without specifying a password. It appears to need no credentials (or the Profile is still lurking around). When I toggle WiFi on/off I don’t auto-connect to XFINITY though, so maybe removing the cert deprioritized it.
I think this is more a MacOS bug that a Comcast bug.