iPhone 6s No sound from speaker or headphones

May 3, 2018
My daughter has a problem with her iPhone 6s. No sound is sent to the speaker or headphones. When headphones are connected, the phone will notice and if volume is changed it appears to affect headphones. In Spotify songs can be changed with the controls on the headphones. And during calls the mic on the headphones work. But no sound can be heard in any app. With headphones unplugged the phone acts like no headphones are plugged in and everything works, even the built in speaker for calls, which means that I can hear the person I am talking to if I hold the phone to my ear old school style. But no sounds can be heard from the speaker, not music, not system sounds, nothing. We have tried:

- restart
- hard reset
- reset personal settings
- software update
- checked every sound setting including mute and do not disturb.
- tried with different headset's, all verified to work in other units.

Does anybody have any tips?