PT8 Internet option is correct (not blocked). I removed A/V again and disabled Windows Firewall.
I can reach registry.paratext.org, but S/R still says “Access to the Paratext Registry has failed due to network or server problem”.
However PT8 prompted me to allow it to update when I restarted PT8. So it must be accessing the network.
I removed and reinstalled built-in WIFI adapter, and I installed a secondary USB WiFi. Same failure.
If I open “Check for Updates”, it says the program is up to date. Which implies network access.