Hi! I'm sorry to hear that you're having trouble with your GPP. Changing the LTE to 5G setting might have caused compatibility issues with your GPP. To try and resolve this, you can follow these steps:
1. Go to your iPhone's Settings.
2. Scroll down and tap on "Cellular" or "Mobile Data."
3. Tap on "Cellular Data Options."
4. Look for "Voice & Data" or "Voice & Data Roaming" and select it.
5. Make sure that "LTE" or "4G" is selected. If it's already set to LTE, try switching it to 4G.
6. If you can't find the "Voice & Data" option, you might need to contact your mobile network provider for assistance. They can provide you with the correct APN settings.
If changing the settings back to LTE/4G doesn't work, you may need to reset your network settings. Here's how to do that:
1. Go to Settings.
2. Scroll down and tap on "General."
3. Scroll down again and tap on "Reset."
4. Tap on "Reset Network Settings."
5. Enter your passcode if prompted.
6. Confirm the reset.
Please note that resetting your network settings will remove your saved Wi-Fi networks and passwords, so make sure you have them written down or saved elsewhere before proceeding. After the reset, try inserting your GPP again and see if it works.
If these steps don't solve the issue, it's recommended to contact the GPP provider or Apple Support for further assistance. They will be able to provide more specific troubleshooting steps based on your device and GPP model.
I hope this helps! Let me know if you have any other questions.