Same with iPhoneX. I had upgraded it to 14.0 version and next day I received "Temperature Warning" and after cooling it down. my Airtel cellular mobile data (4G) stop working, even my calls are getting dropped. I tried all suggested options like: Reset network setting Turn off/on airplane mode Turn off/on cellular data Hard reboot Soft reboot Reset content and data (Factory reset) Turn off/on roaming....etc Nothing helps. Now, I'm frustrated, I had raised case ID also tried to reach out service centers and customer care support but they're suggesting same options which I tried before.