I finally am back in business.
I can’t explain how, but the Edison part of my Reach RTK module somehow had failed.
I was able to flash it from the Windows command line successfully, but the module did not activate the local hotspot, or, connect to my WiFi network.
I replaced the Edison module, flashed it with the Reach image, and it worked just fine.
I tried to recover the original Edison module, but although I could flash it, it never was able to boot successfully. When flashing I always waited minutes to let it finish setting up the file system and boot, but it just never worked.
oh well, I’m relieved!