Same here its 20mbit. with normal wifi (80% of my connection). 3ds however sucks to dl with.
with 32gb internal.
The problem is its STILL 20Mbit max even on 100Mbit broadband which when downloading a large game is annoying.
That makes sense over WiFi, its only capable to around 30-40Mbit at best, but on Ethernet it should be able to hit close to 100Mbit.
That said, even the PS4 only goes around 40Mbit.