I updated my old - now WiFi only iPhone 6 Plus to the 11.0.3 last night and now I have no volume on my phone! The Volume controls simply do not respond now. Even triggering the "Mute/Vibrate" back to on does nothing. If I press up and down on volume controls the volume display shows up but again, does not respond. It also does not seem to change in the Settings or Control Panel. Hard reboot also did nothing to resolve this.No idea! I haven't update this on my working iPhone 8 Plus and won't until I figure out what is going on!