Sorry, you're having issues. I'm assuming that this issue occurs whenever or wherever you're connected to WiFi? I have an issue occasionally at work with wifi... and it's a known issue. Parts of our building get better reception, and I'm unlucky enough to be in one of those areas. At home, I have no problems connecting and downloading via WiFi.
If this happens to you whenever and wherever you're connected to WiFi, then @
bakron1 is 100% correct. You should consider visiting the Genius Bar at your local Apple Store, or, contact Apple Support.
Also, when you get a chance, you might want to consider signing up with iMore. That way we can help you better, and people here are more than happy to help.
Click here to sign up.