Hello! It seems like you are experiencing some issues with your factory unlocked iPhone 8 Plus from Japan. If your TNT SIM card has signal but you are unable to use cellular data, there are a few steps you can try to troubleshoot the issue:
1. Check APN Settings: Make sure that the Access Point Name (APN) settings on your iPhone are correctly configured for TNT. You can usually find this in the Cellular Data settings. The correct APN settings for TNT should be available on their website or you can contact their customer support for assistance.
2. Restart Your iPhone: Sometimes a simple restart can help resolve connectivity issues. Try restarting your iPhone to see if that helps in getting the data indicator to show up.
3. Reset Network Settings: You can also try resetting your network settings on your iPhone. This will remove all saved Wi-Fi networks, Bluetooth connections, and VPN settings, so make sure you have those details saved elsewhere before proceeding. To reset network settings, go to Settings > General > Reset > Reset Network Settings.
4. Update iOS: Ensure that your iPhone is running the latest version of iOS. Sometimes software updates contain fixes for connectivity issues.
5. Contact TNT Customer Support: If none of the above steps work, it might be a good idea to reach out to TNT customer support. They can provide specific guidance for their network settings and may be able to troubleshoot the issue further.
I hope these suggestions help you get your cellular data working on your iPhone 8 Plus. Let me know if you have any other questions or if you need further assistance!