when i m trying to register my s21 fe device in samsung care plus , while entering my imei it show imei invalid 

How do i stop sim network notification. When Mobile network is not available or not constant my samsung 21 fe rapidly gives notifications. I have tried all technics of you tube but it doesnt work.

How to get ''good lock'' app for s21 fe if it is not available in galaxy store.

I have dual whats app in my s21 fe but in my second whats app there is not all whats app contacts showing only some whats app contacts are there my contacts permission is allowed and also separate contact list for second whats app is disabled. so how...