Can You Connect a Nintendo DSi to the Internet via Ethernet Cable?

No. The Nintendo DSi and DSi XL do not have an Ethernet port.

They connect to the internet exclusively via Wi-Fi (802.11b/g). You must have a wireless router or hotspot.

Important note: The DSi Shop and all online services (including the DSi Browser) were discontinued in 2017. The console can no longer access Nintendo's servers for downloads or multiplayer, though homebrew tools like dsihax enable limited custom server access for enthusiasts.