I've already spent an hour or so with support, and have a case number. When I have a couple of hours to devote to this, I'll try again - if I can't get this sorted out another way.
I was hoping that someone in the community might recognize this particular error message and have a suggestion, however.
Alternatively, if I could get access to the "additional tools" and information that they might use, that would be helpful.
Again, my basic question is: If the error message references the Windows Firewall as the source of the issue, why does turning it off not resolve (or at least change) the error message? And why does the Firewall logging show no blocked ports or applications? Could it be that it isn't really a Windows Firewall issue after all?