D-Link DIR-655 User Manual page 28

Section  - Configuration
Visibility Status: Select Invisible if you do not want the SSID of your wireless network to be broadcasted by the DIR-655. If Invisible is selected,
the SSID of the DIR-655 will not be seen by Site Survey utilities so your wireless clients will have to know the SSID of your
DIR-655 in order to connect to it.
Wireless Security:
Refer to page 60 for more information regarding wireless security.
D-Link DIR-655 User Manual