Iphone X freezes when wifi switches to cellular data.

Hello j_wo.

Welcome to Apple Support Communities.

If I'm understanding correctly, your iPhone becomes unresponsive when switching from Wi-Fi to Cellular. I will be glad to assist.

I would suggest Resetting the Network Settings to see if that helps:

Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before.

If you still have an issue, please try these steps:

1. Make sure to remove all of the iPhone accessories and protective cases
2. Make sure that you're running the latest iOS version: Update your iPhone, iPad, or iPod touch
3. Update your carrier settings on your iPhone or iPad
4. Restart your iPhone

Let us know how it goes.

Cheers.

I face the same exact issue with XS Max. I've already raised the issue back when i was using the beta version of iOS 13, but even now that i switched back to the normal/consumer latest iOS version, it hasn't been fixed.

What i've observed is that this happens when the phone tries to connect to a known WiFi (doesn't always happen) and it switches between cellular and the wifi network. the best solution is restarting the phone, but i've seen that toggling off the wifi or forgetting the network and reconnecting sometimes work as well (but not all the time.)

i understand that this might be a special case, but please have someone investigate it.

Happy to provide any logs or demonstrate the issue to a technical team.