Hi - I think I have the problem resolved. This was a physical layer problem.
I have an un-managed switch between the NAS and the pfSense router and the Ethernet cable between those two was not seated properly. Still unclear as to why pfSense was reporting the connection as Active/Online.
In the process of troubleshooting this problem I chose Option 5 of the TrueNAS CLI “Reset All Configuration Data” which (at the time) seemed like a reasonable thing to do since all I had on my mind was network configuration. Now that it is back up I have an empty NAS.
I did an upgrade a couple months back and still have the TAR config backed up locally . I worked through the process here to upload that TAR and now I am back to full functionality:
General Settings Screen | TrueNAS Documentation Hub.