D-Link DIR-300 User Manual page 62

Section  - Connecting to a Wireless Network
3. The Wireless Network Connection box will appear. Enter the same WEP
key that is on your router and click Connect.
It may take 0-30 seconds to connect to the wireless network. If the connection
fails, please verify that the WEP settings are correct. The WEP key must be
exactly the same as on the wireless router.
D-Link DIR-300 User Manual 6