I use my iPhone's personal hotspot feature just about every day, for my laptop when I'm out, or for my kids to stream videos on their iPads. I also typically forget to turn the hotspot off when I get home, and then the next time I need it, the hotspot no longer shows up as an option for other devices to join, even if I turn it off and back on again. Here's how I have been fixing this glitch, in iOS 9 and iOS 10 both.
- Open the Settings app, tap Personal Hotspot, and then turn Personal Hotspot off.
- Go back to Settings, and turn on Airplane Mode.
- Wait for the "Carrier" option to disappear from your Settings list (it is usually the listing directly after Personal Hotspot).
- After "Carrier" disappears, turn off Airplane Mode.
- After "Carrier" reappears, tap Personal Hotspot and turn Personal Hotspot back on.
Usually that shakes out the issues for me, and allows other devices to discover my personal hotspot network again. Occasionally, I have to turn the wifi off and back on in the Settings app of my kids' iPads to force their iPads to rescan for networks correctly, but usually the issue is on my iPhone's end only.