I tried connecting to the RPi hotspot server via a Galaxy S8 but no luck.
I connected via a Win 10 desktop wireless wifi.
(Why would the windows computer connect, but not the linux?)
Then tried PuTTY from WIndows but no luck.
When I interrogate the RPi directly, wlan0 shows inet addr:169.254.160.241
"What was the result when you tried "ssh firstname.lastname@example.org" ?" - You mean directly from the RPi?
If I do that it also states the "network is unreachable".
I think at this point I've invested too much time and not getting anywhere. I got a PX4 and connected to MP in 5 minutes. I think I'll continue to explore Erle as a side project, but it seems clear to me this product is for advanced users only.