In reply to Silverbogan:
IOS 13 is plagued with bugs and I think you’ll have to sit it out until Apple releases fix updates. I’m on 13.1.3 and the hotspot still doesn’t work. Wish I’d waited a bit, i usually do. Internet is full of bug reports for IOS 13.
If you have a recent backup made via itunes, you could restore it and it should go back to IOS 12.