The JayFig78 answer`s did not worked for me.... back to start!

Hi, I've got the same problem since I bought my iPhone X in October 2018 (iOS 13). The only way I found to bypass this MAJOR problem is to reboot the phone or put the phone in air plane mode for almost 30 sec. When I got my phone, I went to the apple store, they have seen the no cellular network problem with my phone, and they gave me a new phone. It ends up with the same result with the cellular network problem. With every OS update I was hoping that the problem will be corrected, and without any luck it's still persist. Will I buy a new iPhone? I'm really not sure.