i’m curious : what kind of things are you doing with your phone to determine that the modem is garbage ??
Since iOS 12.1 update, wireless will just stop sending/receiving data while still showing connection. I will now sporadically lose all cellular signal, until I turn airplane mode on/off, then back to 3 bars.
I've only seen 4 bars on this phone once, at the AT&T store when they gave me a new sim card. Promptly went back to 3 bars when I left the store.