wow a lot of complaining ! my Iphone 7plus has been crashing every 2 - 3 minutes since the update - so I phones apple and it seems that there was a bug in the last update, every time you get a notification it crashes & rebooted my phone so
change your timezone to cupritino USA and date to 1st December and turn off automatic time zone then go into notifications and turn them all off individually then go into software updates and download & install IOS11.2 this will fix the crashing issue - once your phone finally reboots after installation go back and change your times & date and reactivate your notification settings :) simples )