Wifi sometimes doesnt work

Its happend about 3 times in the 2 weeks ive owned the phone. I will be connected to wifi, sometimes for hours and then suddenly i go to load a web page and it just sits there loading. If i go into settings, turn wifi off and back on, it works fine again.

I have read some people having this issue, is this normal to sometimes happen?

 

Btw it still shows im connected to wifi when this happens if thats any help