WEP, or Wired Equivalent Privacy, is a kind of wireless encryption. So if your wireless router is using WEP encryption, it will have a passcode to allow your devices to connect and use it. That is what the DS is asking for.
in the WEP box
It's usually a WEP Key issue.
The 3DS uses the 'same Wi-fi', it support WPA and WEP encryption, which the DSi supported too, but the DS could only use WEP.
It only supports WPA 2 not WEP or others
Wired Equivalent Privacy (WEP) codes are encryption keys used in wireless networks. When configured to use WEP, the network administrator will create a WEP key and then provide it to the network clients. WEP is no longer considered to be secure, and WPA/WPA2 have replaced it in most recent equipment. If you need to access a WEP-encrypted network on your Nintendo DSi, you should talk to whomever owns the network.
The Nintendo DS can only use WEP encryption. The DSi and 3DS can connect to WPA for internet and other internal functions, but only 3DS games and special 'DSi-enhanced' ones can be played over WPA, they are unable to play regular DS games over it. The only real solution is to change your router to WEP.
When searching for wi-fi hotspots, a red lock denotes any hotspot secured with WEP encryption.
In America: A Nintendo DSi is $140; a DSi XL is $160. In Japan: A Nintendo DSi is ¥15,000; a DSi LL is ¥18,000. In the UK: A Nintendo DSi is £150. In Australia: A Nintendo DSi is $300.
tap the Nintendo dsi shop icon on the Nintendo Dsi , or Nintendo DSi XL start up screen
The second Nintendo DSi is the DSi XL.
The wi-fi supports WEP and WPA encryption but any DS game that is not 'dsi-enhanced' can only go online on a WEP connection even though the 3DS can connect using WPA.
Javascript is automatically enabled on the Nintendo DSi. Don't confuse this with Java, which isn't supported.