Well tried a bunch of things, and every upgrade to 2004 or 20H2 destroyed all my mappings, and nothing would allow me to see the other computers on my network. Most of those had automatically updated to 2004 or 20H2, without any issues.
What I think was happening is it there were some virtual wireless interfaces that I couldn't get rid of, even after rooting them out of the registery. I think they came from the wireless pcap drivers that I installed as part of Wireshark. This allowed capture of everything on WiFi. I think that is what did me in, as they acquired 169.254.x.x addresses. Didn't matter if I turned WiFi off and used Ethernet, or a old usb wifi adapter.
It was going to come down to crunch time as M$ is making noise about they are going to start forcing updates beyond 1909 early next year.
Final solution, clean install of Windows 10. Probably a couple more days of getting stuff reinstalled and setup the way I want it, but all my drives are mapped.