Please follow the below mentioned steps in order to resolve the network issue:-
>Do the reset network settings (setting>>general management>>reset>>reset network setting).
>Ensure that network frequency of your device should be selected on Auto-mode.
Menu>Settings> Connections>More Networks> Mobile Networks> Network Mode> Select Auto mode (GSM/WCDMA/LTE).
>Search for the Network Manually by the steps as mentioned:
Menu> Settings> Connections>More Networks> Mobile Networks> Network Operators> Select Manual Search.
>Insert different SIM card in your mobile and check if the issue is resolved or not.
For further assistance, register your concern in Samsung members app (click on “+“icon>send feedback>Error report/ Ask Questions).
Also, We appreciate your valuable suggestion as this would assist us to improve our services.
Will convey the relevant update as soon as possible.
Team Samsung Members