Thanks HelenC!  Maybe double check that, @SwimDad . I don't know if that's different than 'protected browsing'.

I'll let you know when/if we deploy this certificate change on Friday. You can see from posts like this that other sites have run into this with xfinity: https://forums.xfinity.com/t5/Your-Home-Network/your-connection-is-not-private-problem/td-p/3351709.... but I can appreciate it'd be impossible to work with them further on this, and nobody wants to be stuck between two companies pointing fingers at each other.  I'll be around over the weekend if we need to try more stuff.   In the meantime one test you might be able to run, if you're technical, is to tether your computer to your phone and try the url test (or use a trusted neighbor's non-comcast wifi). If you still can't access the file https://prodldfp.proseries.com/fa/2020/windows/proseries_core/S2020COI.xml then the issue might be a firewall on your computer.