Topic: 3DS: New updates failing/taking my time

So I finally wanted to use my 3DS since the last update, but every time I try, it takes a long time before getting halfway, failing and getting the message that there's a problem. I then have to do it again to only repeat the same thing.
Can someone explain why it takes so long to update and why it fails? I don't want to keep trying to update and then fail again while it tears away my internet credit.