Further research has revealed this is a common issue, different ringtones for each SIM is a built-in Android feature but the controls for this are commonly not included by dual-sim phone manufactures. I found two apps to address this; DualSimRinger by mdn worked https://play.google.com/store/apps/de...

How do I a set a different ringtone for each sim?

I went through all the usual resets and then swapped the SIMs before hotspot worked. Clearly, performance may vary in this respect, it may even only apply to some carriers, just another factor to be aware of. Using Build V0.1_20170803 Since other than this It's working I intend to wait for Android 8...

It seems that while the phone can use data from either SIM The hotspot can only connect to the internet via the SIM in slot 1. Not a problem now I have discovered this but I thought I would flag this to save others the same problems I had. It would be good if an error message was displayed if the ho...