Please do not use WEP encrption in wireless link. It is very insecure in current standard and with current powerful hardwares. It is easy to crack within a few hours. Try to use WPA / WPA-2 instead.
If you are talking about this as below, it should be ok to disable it. (I am using DIR-655)
Wi-Fi Protected Setup
Enable
Enable the Wi-Fi Protected Setup feature.
Lock Wireless Security Settings
Locking the wireless security settings prevents the settings from being changed by any new external registrar using its PIN. Devices can still be added to the wireless network using Wi-Fi Protected Setup. It is still possible to change wireless network settings with Manual Wireless Network Setup, Wireless Network Setup Wizard, or an existing external WLAN Manager Registrar.