iPhone 6 calls cut out

When using my phone when in my car it is connected to the car audio via bluetooth. This worked flawlessly with my iPhone 5s. Now that I have upgraded to the iPhone 6 calls cut out ever few seconds. I found that if I disable wifi the calls stay rock solid as they did with the 5s. I have Verizon so I don't have wifi calling. Why would it do this. Seem like some kind of firmware issue. Called apple and they think it is my device. I did some searches and it seems others have this issue as well.