iPhone 6s Plus, restarting again and again.

Hi, anyone had this problem ? My iPhone works like 2-3 minutes, after that it's restarting itself ...

I have this problem since I updated the software to 13.6 ... before that , the phone worked perfectly.

I also contacted Apple support , they said that it could be the battery and I don't think so.

Has anyone encountered this problem before?

Any fix?

Please.