This sounds spookily like our issue. My wife's iphone X stopping being able to connect to the cellular network, despite wifi working. Tried everything apple suggested: carrier update, software update, rebooting, sim removal and replacement, reset of network settings. Finally the support agent suggested I backup and restore the phone -- now the phone is blank with the same issue and it is refusing to activate over the wifi -- so despite the phone working fine before with the exception of cellular we now have a bricked phone and my wife's data is backed up and inaccessible. Repair was quoted at roughly the cost of a replacement so we've had to buy a replacement iphone... Couldn't wait 3-4 weeks for the repair. Could be a hardware fault I suppose but if it's a software fault due to ios 14.2 we shouldn't have to buy a new phone really. Also why does a restore of ios mean the phone is bricked... Really feel let down about this.