IPhone 5 Wi-Fi not working when phone case is on? - 1

I don't understand why this keeps happening. I obviously need a case on my phone, but every time I put a case on my phone, the Wi-Fi doesn't work. It's any case- not just certain ones. What do I do?! No one else seems to have this problem.

Are all your cases of the same material? And do they happen to be a type of hard plastic?

I had one and they same effect would happen to me, I didn't purchase a case of that material again. The material seems to absorb the Wi-Fi signals. I got a Spigen case instead and a customized one that had a har back plate (with a picture) but flexible sides and those wouldn't mess with my Wi-Fi.