We can give it a shot, for sure.

First, please fire up a browser and try these two links on the machine that is having an issue: 

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

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

They both go to the same file.. it should look something like this, but might vary depending on browser.

If you are experiencing the problem it sounds like, probably the first will fail with some error message and you'll get the second as shown above

Upon confirmation, we can explore fixes. By chance are you a comcast/xfinity customer with "Protected Web Browsing" enabled?  We know that's giving some folks issues.. we've also run into issues with routers & firewalls.