libresensor2 not pairing on a permanent basis with my iphone 11 xr

My libre sensor 2 is not pairing permantley with my iphone 11 xr, it does then goes and its driving me mad. Have spoken to Abbott and they tell me to do a few things, then it works the. goes again. i had the libre 1 sensor but doctor has prescribed sensor 2 as im having a few hypos.

Even deleted libre app and restarted it. Done everything , it is so frustrating and a huge worry to me

Thankyiu