Ive got a Draytek Vigor 2860 too, so that rules out the Smart Hub then being a problem.
Curious that it doesn't affect the S versions. There must be something a little non standard about the BT Whole Home Wifi then that the iPhone can't cope with.
Have you contacted Apple about this issue? Seems like a bug with the iPhone not handling an error or condition properly if it's only on specific models and goes as far as crashing the phone?
