I have already shared this issue here with my 6s switching off randomly after updating to 10.1.1 and made a reference video of what happens right after it switches off. Here it is: https://youtu.be/nexd2ItlgjU
Raise a bug with Apple ( https://developer.apple.com/bug-reporting/ ) and share your experience by creating videos of the issues happening. Seems like it's not just 6s being affected and not just a hardware issue in most cases.