What do I do if Broadcast SSID is turned off on my router?
If the SSID Broadcast settings of your router are turned off, the Nintendo DS will not be able to detect your access point. There are two things you can do in this situation.
You can enter the name (also known as the SSID) of your access point into the settings of the Nintendo DS. Doing so will let the DS find your access point and connect with it.
To enter the SSID into the DS, go into the Nintendo Wi-Fi Connection Settings of the Nintendo Wi-Fi Connection Setup screen. Tap the Connection you would like to edit, and then Manual Setup. On the following screen, tap "Edit" on the SSID line, enter the SSID of your access point, and tap "OK." Tap "Test Connection" at the top of the screen to complete the setup.
You can turn the SSID Broadcast on. Doing so allows the Nintendo DS to detect your access point when you select "Search For An Access Point" in the Nintendo Wi-Fi Connection Setup screen. Once the connection is complete and the test connection is successful, you can turn the SSID Broadcasting back off. The Nintendo DS now knows the name of your access point and will still be able to locate it.