iPhone 7plus WON'T connect to neither the Apple Store nor iCloud
My dad has had his iPhone 7+ for a long time now. A few months ago after an update the phone refused to connect to the Apple Store (which makes him unable to update any apps, download any apps, use iCloud, etc). We have reseted the phone, erased it and tried backing it up with iTunes, but now we ended up with a phone that still doesn't connect to the App Store, but now it's worse because it has no apps, since the phone just WON'T connect.
Every time we try connecting to the App Store, or iCloud, we're able to put the email and password, but it doesn't do anything, it's as if we didn't plug any of those details in.
Does anybody know how to fix this? I've searched everywhere and I can't find a way to fix this...