Hi John,
if you try a personal hot spot on your phone, make sure it creates a 2.4 GHz WiFi. Current iDevices by default open a 5 GHz WiFi, only if you select "maximize compatibility", they do 2.4 GHz, for example.
For your home WiFi, also make sure it's 2.4 GHz and if in doubt, take Mesh or Thread routers out of the equation, try with the base station only.
I'm also not sure what happens, on different routers, if you hide your SSID for example.
As a last resort, please create a service request at vstabi.info/devices (My Devices) if you haven't already done so, and we will see to it.
Kind regards
Eddi
Born to fly ...
forced to work.