Hello phatharawan,
Thank you for using the Apple Support Communities! Based on the details you've shared, you are unable to use your Personal Hotspot since iOS 13 update. I am happy to assist.
I appreciate all of the details you've provided, and the steps you've taken so far. Please try the steps below next. Be sure you are testing your Personal Hotspot after each step. If the issue resolves after a particular step, you do not need to complete the remaining steps listed:
-Update your carrier settings on your iPhone or iPad - Apple Support
-Install any and all updates that may be available for the connecting devices; your PC and Sony Smart TV. You may need to work with the manufacturer of these devices to do so.
-Restart the broadcasting iOS device; your iPhone.
-Change the name of your iPhone: Settings > General > About > Name.
-Reset Network Settings: Settings > General > Reset, then tap Reset Network Settings. Please keep in mind, this also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you’ve used before.
-Reset All Settings: Settings > General > Reset > then tap Reset All Settings. Please be sure you complete a back up of your data prior to this step.
Learn more about Reset Network Settings and Reset All Settings here: Return iPhone settings to their defaults - Apple Support
I would also like you to make sure you've covered any additional steps found here, which can be more specifically helpful for the issue with connecting to your Sony Smart TV: If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi + Cellular) - Apple Support
Reach back out if the same issue continues.
As an additional side note, now that you are using iOS 13 and have a PC, please also keep in mind, if you sync your iPhone to your Windows PC, you will need iTunes version 12.10 for Windows, which adds support for iOS 13 and later: iTunes - Apple
Take care.
