Antenna House Excellent For The Working Engineer And Serious Student What Is The Matter With My Wireless Setup?

What is the matter with my wireless setup? - antenna house excellent for the working engineer and serious student

I try to send Internet at home with my girls from the 500 meters. I connected a wireless router to a dBi parabolic antenna of 18. I have a destiny. The computer tells me that I connect an excellent relationship, but when I try to use the Internet that said, I have little or no connectivity. I have also just outside Linksys wireless card when I plug in the USB port and disconnect the antenna of 18 dBi at home computer says I have a weak signal, but when I try to connect to the Internet, they connects, but is quite slow. Why not start with the big antenna and a very good signal and work with a small with a weak signal. Thanks