You can not fix it.
The cumbersome turn on/off auto time and locations or reboot or reset your phone sometimes give a very temporary relief.
I have done everything suggested in this thread, everything suggested by other threads, everything suggested by customer service and by friends.
Anything you do to try to fix it will at best be a temporary fix.
This is not a matter of your settings. It is not a software issue. My phone and yours have hardware problems. One person in this thread mentioned that you can tae it back to the store under warranty BUT if you replaced the screen, it can be related to the problem and it apple will tell you it is your fault. In my case, I bought a used iPhone an replaced the screen. The only solution is to where a watch. Missed messages from people not in my contacts and other issues just are.