on 10-08-2021 14:06
i recently upgraded to iphone 12 on O2. since then i have had terrible signal and next to nil data access. 4g in my area is very poor and 5g is non existent . my old iphone 8 allowed me to use 3g which was fine but i can now not access this facility on new phone. is this an apple issue or O2 issue.
on 10-08-2021 14:17
The network options are set by the carrier file installed on the phone.
Check to make sure you have the latest, but I wouldn't be surprised if O2 have removed the 3g only option.