My iphone 5 (ios 8.3) cannot connect to some of the wifi hotspots.

At home, it was able to connect for the first time. After that, sometimes not able to connect, sometimes said password incorrect but sometimes connected automatically for a short while and then discount.

For some wifi hotspots, it does not have any problem at tall. However, I tried the wifi (password required) in hotel, it always said incorrect password.

I checked on the Interent and someone said it is a known problem for iPhone 5. I tried their solution such as router setting, restore the phone, reset the network setting but doesn't work.

When the phone connected to other phone via wifi hotspots (tethering), again no problem at tall. I can concluded that it is not hardware problem.

Any specific router settings required for router?