Q: iPhone 6 sound doesn't work unless on wifi

My iPhone 6 Plus sound will not work unless the iPhone is connected to Wi-Fi.  When I'm away from my house the iPhone switches to Verizon LTE and works normally, except no sound.  I noticed this when I was trying to watch videos I downloaded from iTunes.  As soon as I get back home and the iPhone connects to Wi-Fi, the sound comes back.  The iPhone is not set to mute.  The iPhone has the most current iOS installed.  Any suggestions?