Fails to remember my iPhone hotspot

I have removed my broadband as I don’t have a need for it anymore.
I use my iPhone hotspot and connect all my devices (fire tv, smart tv, Alexa etc)
The trouble is that Volumio fails to remember my iPhone hotspot and I have to use a second iPhone every time, connect to volumio’s hotspot and then point volumio to my iPhone hotspot ( and add the password every time)
Why doesn’t it remember? And what can be done to get it to remember?