Internet connectivity lost after Norton uninstall - Solved
The symptom is as described in the title.
I know this has been asked and answered before and there are lots of people struggling with it.
I had stopped using Norton a long time ago since my "free" subscription from Comcast had expired. I was getting Norton nag screens to renew frequently but sort of ignored them until they got too bothersome, so I decided to permantly uninstall it.
I followed all the recommended procedures, including using the "official" Norton uninstall script and searching for remnants of Norton files. No luck. I then tried running the uninstall script with system integrity protection disabled (this has to be done in Recovery Mode) thinking that there were some files locked by the system. Still no luck. In desperation, I even re-installed Big Sur.
Despite all that, Norton Security was still popping up in network preferences - attempting to start but failing.
The answer (for me at least) was to restart in safe mode, examine network preferences, select Norton in the list, and click on the minus (-) symbol to remove it.
After a reboot, all is well - Norton disappeared from Network Preferences and is no longer blocking internet connections.
Hope this helps others. As has been stated many times, Norton is not great on Macs, a fact which I wish had known a couple of years ago when I installed it.