My Iphone 6 won't connect to wifi at all!

I recently got iphone 6 , and I tried connecting my iphone 6 to at least 5 wifi routers , everytime I got an error of wrong password or unable to connect to wifi.
When I took it to the apple store ,my phone got connected to their wifi router but stopped completely once i reached home ,
I have even updated to ios 8.1 !!

PLease help me !