D-Link DIR-850L User Manual page 48

Section 4 - Security
If you selected Automatically, the summary window will display
your settings. Write down the security key and enter this on your
wireless clients. Click Save to save your settings.
If you selected Manually, the following screen will appear.
Create a passphrase for your Wireless Security Password. Click
Next to continue.
Note: The security password/passphrase must be between 8 and 63
characters and is case-sensitive. You will need to enter this passphrase
on your wireless clients exactly or it will not connect.
D-Link DIR-850L User Manual 43