Q: Iphone 6 wifi is rarely working

I updated my IPhone to ios 9.3.2 couple of weeks back and noted that the wifi reception has become very bad. It detects any wifi network only if I am very close to the router.

Also in some cases even if it detects the network (only when I am close to the router), it says invalid password though I am 200% sure that the password is right. My android phone detects the same wifi network couple of rooms far from the router and it works fine.

There is this other instance, when my friend who is using iphone 5s (9.3.2) whose phone detects more than 6-7 wifi network in a shopping mall and my phone didn't even detect a single network and we both were standing in the same place. Please note that I have done all the solutions given in the forums including, reset network settings, force restart, reset as a new phone etc.,

At times even the cellular network and GPS is not working properly. Though this is not always the case.

It is not of much use without connecting to internet. It would be really helpful if I get a closure on this problem.