Personal hotspot is off and greyed out.

On an iPhone, the Personal Hotspot feature is not a standalone service. It is entirely dependent on your carrier’s network plan and permissions. Your carrier provides the actual data service through the SIM card, while the iPhone simply offers the interface and tools to share that connection.

When you enable Personal Hotspot, your iPhone acts as a bridge:

• It takes the mobile data provided by your carrier.
• It broadcasts that data connection over Wi‑Fi, Bluetooth, or USB.
• Other devices can then connect to your iPhone and use the same data plan from the SIM you’re actively using.

In short, the iPhone doesn’t generate internet access on its own—it only provides the mechanism to share your carrier’s data service with nearby devices. Whether the hotspot works, and how much data can be used, is controlled by your carrier’s plan, restrictions, and billing policies.

A mobile hotspot can be tethered through USB, Wi‑Fi, or Bluetooth, giving you flexibility to choose the method that best suits your device and situation. In fact, these options aren’t mutually exclusive—you can even combine them in different permutations, allowing multiple devices to connect simultaneously through varied channels. (See the illustration below for a visual breakdown.)

The Hotspot is a carrier-specific feature. Contact your Carrier (Cellular Service Provider), the agency that issued the SIM / eSIM to you.

To activate this feature for the SIM card you are using, it is imperative to reach out to your respective mobile carrier. Contacting your carrier allows you to seamlessly enable the hotspot on your device, ensuring optimal compatibility and performance. Moreover, it is advisable to inquire about any potential limitations associated with using the hotspot feature.

Different carriers may impose specific restrictions or offer varying levels of accessibility, such as data usage caps or speed limitations. Understanding these nuances ensures a smooth and informed experience when utilizing the hotspot functionality on your iPhone. Therefore, for a comprehensive understanding of the capabilities and constraints related to your specific carrier, direct communication with them is highly recommended.

See the Pic below the Hotspot is made available based on the Mobile Data selected and the feature that is enabled by the Carrier

Please see the pic below to make it clearer that Hotspot is enabled by a Carrier on one SIM and not by the other Carrier in the same iPhone (Dual SIM).

Use these steps first

Restart the iPhone or iPad that provides Personal Hotspot and the other device that needs to connect to Personal Hotspot. Make sure that you have the latest version of iOS. On the iPhone or iPad that provides Personal Hotspot, go to Settings > General > Reset, then tap Reset Network Settings.

If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi

Also, check the following

1. Network coverage and stability
2. Data Balance
3. On your windows (See if WiFi Auto Joins is enabled)
4. Also, check if you have any stronger WiFi signal around your computer.

Ask the Carrier to change the SIM if nothing works.

The "other devices" in your iPhone's personal hotspot usage typically refers to any devices that have connected to your hotspot to use your phone's internet connection. Even if you don't use a computer, laptop, or tablet, other devices like another smartphone, a gaming console, or even a smart TV could have connected to your iPhone's hotspot, consuming data.

See the pic below. Samsung here indicates Samsung TV

The iPhone itself does not disconnect a hotspot and does not have settings to override any limits imposed by your cellular service provider.

1. Carrier-imposed Data Limits: Many carriers enforce data caps or restrictions on hotspot usage. If you exceed a specific data allowance for the hotspot, the service may slow down or disconnect entirely until the next billing cycle or unless additional data is purchased.
2. Time Limits: Some carriers impose time-based restrictions on hotspot usage, automatically disconnecting devices after a certain period of continuous use to prevent excessive consumption of network resources.
3. Network Prioritization: In periods of high network congestion, some carriers prioritize direct mobile data usage over hotspot connections, causing the hotspot to disconnect intermittently.
4. Device Restrictions: Certain carriers limit the number of devices that can be connected to the hotspot simultaneously. Exceeding this limit might cause disconnections.
5. Roaming or Out-of-Coverage Areas: If the iPhone is in a roaming area or experiencing weak network signals, hotspot performance may degrade, leading to frequent disconnections.

To address the issue, contact your carrier for specific details about your plan's hotspot terms and limitations. They may offer solutions, such as upgrading your plan or adjusting network settings.