72D-Link DIR-412 User Manual
Section 4 - Security
From the Setup > Wireless Settings screen, click Add Wireless 
Device with WPS.
Add Wireless Device with WPS Wizard
PIN: Select this  option  to  use PIN  method.  In  order  to  use this 
method you must know the wireless client’s 8 digit PIN and click 
Connect.
PBC: Select this option to use PBC (Push Button) method to add a 
wireless client. Click Connect.
Select  Auto to add a wireless client using WPS (Wi-Fi  Protected 
Setup). Once you select Auto and click Connect, you will have a 
120 second time limit to apply the settings to your wireless client(s) 
and successfully establish a connection. 
If you select Manual, a settings summary screen will appear. Write 
down the security key and enter this on your wireless clients.