Follow the Method 3 in this link.
https://www.pingzic.net/mobile-network-not-available-fix/
NOTE: Instead of GSM auto prl select LTE/CDMA/UMTS auto(prl) 4g is going to work
https://www.pingzic.net/mobile-network-not-available-fix/
NOTE: Instead of GSM auto prl select LTE/CDMA/UMTS auto(prl) 4g is going to work