Bluetooth slow to turn on after iOS10 update
I'm having this issue as well. I went to Apple, they replaced my iPhone 6S due to both the bluetooth coming up with an error in diagnostics, as well as the battery issue thats plaguing 6S users. However, I am still having the same problem. I am convinced its software related and waiting for the new iOS patch. A bit concerned that the hardware diagnostics at the Genius Bar found a Bluetooth error as well, hopefully the software isn't damaging the hardware.