As much as I love my iPhone, I know they can be very buggy.
My iPhone keeps disconnecting from my Wi-Fi - however I have full Wi-Fi signal and it even does it when there's no one else in my house connected, I'm not too far away from my router and no one in the house has problems, only my iPhone.
The volume on my iPhone keeps disappearing too, sometimes when I turn the switch on the side to loud no sounds come out of my phone, other than alarms and if someone rings me. When I try to turn the volume up, it only comes up with the 'ringer' icon, and when the volume icon does appear, the bars to show you how loud your iPhone is completely disappears.
I have the newest update as I only got this phone a month or two ago, any help is greatly appreciated!