An account complains about iPhone not accepting SIM after upgrading to iOS 12.1.4.
Another account says your iPhone cannot connect to wifi.Or even, there are faulty users who cannot use both data and Wifi.
Notice of smartphone cannot receive sim.
Apple's @AppleSupport account gave feedback under a few tweets, but most were directed to its support page, not giving a specific fix.
Hopefully, Apple will really fix these serious bugs in the next update, and of course not adding new bugs.