Why does my iPhone 6 Plus sometimes disconnect from Wifi?

[iMore Question]

I bought a brand new iPhone 6 Plus a month ago.I didn't use it for anything else but calling and texting in the beginning but I've recently been using it for media,web browsing,YouTube and so on.I've noticed that my phone sometimes disconnects from wifi itself especially when on lock.When I unlock it it automatically reconnects.Sometimes it randomly disconnects while I'm using it.The only way for me to fix this is either press forget network and then connect to it again or just reboot my router.Is that normal?Is it my phone or is it iOS 8.1.1?Help pls?

 

[kch50428]

That's not a bug...its a feature. When locked, the iPhone's wifi will "sleep" when not needed to help conserve battery...