iPhone 5 - WiFi Connection Problems

Hi,

I bought my iPhone 5 at Texas on March this year. It worked perfectly find until last week when it started to have problems connecting to SOMES WiFi connections. The strangest thing of all this is that I can no longer connect to my home wifi network as I always used to be!

This last weekend I couldn´t connect on the Hotel but then in the airport I could connect. Also I could connect in the airplane, but then again I couldn´t connect on my home.

Do you have any idea of what is going on?

The message that appears on the screen is: ""unable to join the network...."

I´m thinking now that the problem seems to be when I have to put a password. Both in the airport wifi and airplane wifi, the log in is made via browser. Any idea?

Thanks!

Juan.-