Apple ID not working on cellular data, but working on when i connected to wifi.

If your Apple ID is not working on cellular data, there could be a few possible reasons for this issue. Here are some troubleshooting steps you can try to resolve the problem:

1. Ensure that you have a stable cellular data connection. Verify that you can access other internet-based services using cellular data, such as browsing websites or using other apps that require internet access.
2. Turn off Wi-Fi on your device to force it to use cellular data exclusively. Sometimes, if Wi-Fi is enabled but has a weak or no connection, your device might not switch to cellular data automatically.
3. Verify that you have an active cellular data plan with sufficient data allowance. If your data plan has been exhausted or suspended, some services, including Apple ID authentication, may not work.
4. It's possible that there might be a temporary issue with Apple's servers. You can check the system status on Apple's website (Apple - Support - System Status) to see if there are any ongoing problems.
5. Make sure your device is running the latest version of iOS. Updates often include bug fixes and improvements that can resolve issues.
6. Go to "Settings" > "iTunes & App Store" and tap on your Apple ID. Choose "Sign Out" and then sign back in using your Apple ID and password.
7. Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
   1. Restart the device. That's it.
   2. Still not solved --> Force restart iPhone - Apple Support
8. If the issue persists, you can try resetting all settings on your iPhone. This will not erase your data but will reset all personalized settings to their default values. Go to Settings > General > Transfer & Reset > Reset > Reset All Settings and confirm the action. Note that you will need to reconfigure your settings afterward. All settings—including network settings, the keyboard dictionary, the Home screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.
   1. Reset All Settings: Return iPhone settings to their defaults - Apple Support:- Return iPhone settings to their defaults
   2. You can return settings to their defaults without erasing your content.
   3. If you want to save your settings, back up your iPhone before returning them to their defaults. For example, if you’re trying to solve a problem but returning settings to their defaults doesn’t help, you might want to restore your previous settings from a backup.
9. Make sure you have the latest updates installed.
   1. Update Over-the-Air (OTA) —> Update your iPhone or iPad - Apple Support (IN)
   2. Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)

If none of the above steps resolve the issue, it is recommended to reach out to Apple Support or visit an authorized service center for further assistance. They can provide specific guidance based on your device model and iOS version.

By following these steps, you should be able to determine the cause of the issue and, in many cases, resolve the problem with your Apple ID not working on cellular data.