For more information, you will need to contact your carrier's support team and raise the issue with them. However, on some occasions, the carrier might have permanently disabled the option on your account. If you know the codes, you can add them by going to Settings > Cellular > Cellular Data Options > Cellular Network or Settings > Mobile Data > Mobile Data Options > Mobile Data Network. Missing APN data can also be the culprit. The solution might be as simple as sending an SMS to your carrier to enable the setting. Sometimes, a quick search on your carrier's FAQs will solve the problem. Often, there will also be a spinning wheel alongside it. You might find that the tethering option is entirely grayed out in the Settings menu, or you might see an onscreen message that reads To enable personal hotspot on this account, contact.
This issue manifests itself in a number of ways. The problem is most prevalent on locked devices that you've bought directly via a carrier's shop, but it can happen on unlocked phones and tablets too. For reasons that aren't always entirely clear, some carriers disable tethering on their devices.