This may sound like a dumb question, but the file extension for your rom is .3dz right?
Error 002-0123, btw
Lol, a quick google search says you're unable to connect to an access point.
Did you use the correct chip code?
I generate a random one in Rom Patcher.
Pokemon and Animal Crossing are CARD2 games, so you need a CARD2 header for this. Try Pokemon Y header here: https://gbatemp.net/threads/scene-roms-online-tutorial-for-dummies.370589/ or find some online ready ROMs on certain sites.
Is your 3ds connecting online?Im using a Pokemon X header for OR/AS with chip id ending in 98.
I get Error 002-0123, too.
The header is from my dumped Pokemon game, so I'm wondering what might be the issue.
Oh it works now, I changed the chip id to OKI Semiconductor (AE FA 00 90)
Header is from my Pokemon X (Chip 2 I guess)
isn't the chip id AE F8 00 98?
Since the card is 2gb (F8) and card 2 (98).