Context
I have purchased a new Dell XPS L502x laptop which has Windows 7 64 bit Home which has this Wi-Fi Option: Intel ® Centrino ® Advanced-N 6230 (2x2 agn + Bluetooth)
And I have 4 Mbps Internet connection with Dlink DIR-655 Wireless router.
Problem
When I use internet on my laptop by wired LAN it works very good very fast. But when I use internet on Wi-fi it works very slow and most of the time doesn't work properly.
Any solution for this?
Screenshot 1
This is screenshot of Wireless Router setting

Screenshot 2
Of device Manager

Screenshot 3
Network setting folder

Please tell me if you need any information to solve this issue.
