iPhone 6 not connecting to WiFi

Hello there ,

i have a problem in wifi connectivity with my iPhone 6

my iPhone 6 iOS 8.3 64 g bought it from October 2014 is always having problems wifi connection , sometimes it used to see wifi networks and to connect to some and refuses to connect to others and few times it connects fine ,

but the problem occurred about 4 months ago that now I can't even see the networks around and when it sees any of these networks and you put the correct password It keeps on saying it s a wrong password !!!!

I Did everything to fix this problem , reset network , I deleted everything and then I restored from the backup and the same problem is still here 😢😢

does this mean that this is a hardware problem ?!??

looking for help !!!

THanks