1. Iphone 7 automatically shuts down; 2. cant connect automatically to internet

1. It is gets frequent occasion that my Iphone 7 automatically shut down. There are times that it shows that it needs to be plugged in but battery indicates that there's still charge.
2. My iphone will not connect to internet automatically. WIFI on settings is off so I click it to turn it on but wifi button does not turn on.

Appreciate your help.