This is about how to prevent your 2/3DS from incidentally firmware updating.
Here is a easy way.
- Download the PokGear App.
- Open the app and go to the menu screen, switch the 'Enable QR Section'.
- Set the ip 159.203.242.044 as your 2/3DS' DNS. That's it!
Here is a tutorial video of how to set DNS on 2/3DS.