@robert-hh that did it! router.us.thethings.network was the key! Nowhere do I see that URL on TTN gateway config, so you really saved my bacon there. Thank you!

@robert-hh Thanks. I did the os.mkfs('/flash') and then ran Pymate on my phone to re-establish a WiFi connection and reinitialize the chip (repopulating with main.py and boot.py) that I now see in ftp.

Just managed to update my pair of LoPy4s using lopyupdate from pycom_firmware_update_1.10.0.b2.tar.gz on Ubuntu 16.04 x86_64 and all is good. Now running 1.14.0.b1. My code using PyTrack GPS, wifi, MQTT, LoRa.LORA with socket.SOCK_RAW and AES with HMAC-MD5 all working as before with the old-fangled LoPys. I guess the dust has settled :) Edit: One LoPy4 was programmed on the Exp Brd 2 with jumper cable and the other on a PyTrack.