D-Link DIR-859 - Why can’t I connect to certain sites or send and receive e-mails when connecting through my router?; Can I connect the DIR-859 to an existing router?

81D-Link DIR-859 User Manual
Section 5 - Connecting to a Wireless Network
WPA/WPA2
It is recommended that you enable wireless security (WPA/WPA2) on your wireless router or access point before conguring
your wireless adapter. If you are joining an existing network, you will need to know the security key or passphrase being used.
2. Highlight the Wi-Fi name (SSID) you would like to connect to and
click Connect.
1. Open the Windows Vista® Wireless Utility by right-clicking on the
wireless computer icon in your system tray (lower right corner of
screen). Select Connect to a network.