iPhone 7 acting weird post iOS 11 upgrade

After upgrading to ios11, I frequently come across the scree aaking for passcode in case of restart. I’m not sure if my phone has been restarting itself when I’m not using it. And once I provide the passcode, I start getting notification one after the other for all the unread text messages. I had some 1k unread operator and promotional messages which started popping up on my screen one by one starting from last to first. To stop them I had to mark read to all the messages, otherwise would have recieved a thousand msg tones.

Secondly I have started facing charging issues at times. Like, when I plug it in it shows the charging symbol but the battery percentage goes down. Then at the same power point I restart the phone and plug it back and it strts charging.

Are these issues only observed by me or others are ha ing the same problem?

Any idea what may fix this?