I have the same problem as DeafeningSilence on my iPhone 7. Used 1.5years. Wtf is going on?!! Boot time is about 5min. Once I got it to work normally, booted normally, voice memo and calls working but then after couple calls it got fked up again. No sounds when calling ( no speaker option) and there is no sound when taking videos. YouTube and Spotify works normally though. Now I can call but nobody hears on the other line nor do I hear them. App calls like messenger or WhatsApp doesn’t even wanna connect neither through video calls . Even with WiFi/4g working properly.
Also when I connect headphones which are btw brand new the phone doesn’t recognise them. But then again.. by Connecting with Bluetooth headphones The phone seems to work normally.
I’ve Tried everything from restoring as new phone etc with no luck.