Apple has released an iOS update (10.1) which will fix the hotspot issue. To update to iOS 10.1, go to Settings > General > Software Update.
We've confirmed the issue that some of our customers have been experiencing accessing Personal Hotspot with iOS 10 is due to carrier settings which need to be updated by Apple.
Our networks team is currently working with Apple to get this resolved and this will be pushed out to devices as soon as possible.
We'll update this article as soon as we get further information.
What can I do?
Apple have advised a workaround while this issue is investigated:
Switch your iPhone to 3G first by going to Settings > Mobile > Mobile Data Options > Voice and Data > 3G
Update your hotspot APN by going to Settings > Mobile > Mobile Data Options > Mobile Data Networks >Change Personal Hotspot APN to connect
Once the APN has been updated, switch your phone back to 4G in Settings > Mobile > Mobile Data Options > Voice and Data > 4G
If that doesn't work, turn your phone off and on again, then reset the network settings in your iPhone. Go to Settings > General > Reset > Reset Network Settings. Please note this will clear all your stored WiFi passwords.
Should the above steps not resolve the issue, contact us so we can add your details to our investigation.