A friend has an iPhone 6 and a plan that includes tethering.
A couple of weeks ago, her "personal hotspot" feature started acting up. It tends to be inactive. When you try to activate it, you get a message asking to contact the cellular provider.
Turning the phone off and on again solves the problem.
The provider maintains that tethering is activated, and that there is no problem on their end. I checked the cellular data settings and they are OK.
What could be causing this?
Could it have been caused by a software update? iOS is up to date.