Thanks for confirmation! If you have time, could you turn "web protect" back on and try these two links in a browser? 

https://prodldfp.proseries.com/fa/2020/windows/proseries_core/S2020COI.xml

https://perdldfp.turbotax.com//fa/2020/windows/proseries_core/S2020COI.xml

I think the first won't work for you and the second will... but would like to validate the theory.  Forever we've been using a common practice of associating multiple domains with our server certificate. Turbotax.com is the primary, and a bunch of other domains are listed as alternates - including proseries.com. We're wondering if that is what is triggering things. I'd love to get it changed if it is, so you can go back to having that on full time without conflict.