I have tried to connect using external IP from another computer in LAN, but it couldn't. I thought maybe it was because both computers were in the same LAN and so to check it I have installed an application to my Iphone. I have closed the connection of the mobile to carrier, so it was just connected to my LAN. And, SURPRISE!!! From the application in my Iphone, using external IP, I could connect to Qt4 Fortune Server Example and got response!!! So, the problem is not trying to connect using external IP from within the same LAN; because Iphone could connect with another application. So, anyone has idea, why Qt4 Fortune Client Example CAN NOT connect to Fortune Server Example using external IP ?