I don't personally own an IPhone 6 but it does appear that it can have some significant glitches related to Bluetooth devices. According to this review, your best bet is to go into your phone and delete any Bluetooth pairings that you've made, reset network connections and then try to re-pair your phone and device.
If that fails, a possible solution might be to factory reset your phone and fully update with the latest iOS.
Here's a detailed guide on possible solutions as well.
