Thank you! This solution (change to registry keys in .NET) worked. To recap for other users whose software cannot connect to update or download state, my error was:
"Could not connect to the update site. Error 42003: The underlying connection was closed: An unexpected error occurred on a receive." and, in details, "The client and server cannot communicate, because they do not possess a common algorithm."
I hope that TurboTax will add this to the information they provide through Customer Care.
