Wow.  Bummer.  First off, I'd like to mention that in the past two times I called Nintendo asking for help, I ended up helping the customer service person because I knew more about the 3DS system than he did!  So pretty much, the Tech Support guys don't actually know a lot.  Also, it seems weird that Nintendo would claim to have sent you a brand-new system when your serial number was exactly the same.  That's not right.

I looked up the error code on Nintendo's support website; nothing useful there.  However, maybe your router has certain configurations that do not work with the 3DS.  To diagnose, head on over to a Nintendo Zone (all wireless configurations there should match to the letter on the 3DS), and then see if you can view your friend list properly.  Also, try playing games online.  If it really doesn't work, that means that your 3DS's wireless is malfunctioning, or there is a problem with the 3DS operating system.  Call Nintendo and tell them EVERYTHING, then ask them to literally replace your system, if possible.

Good luck!

Stuff like this probably wouldn't be a hardware issue. It's unlikely that the wireless is messed up in JUST such a way as to prevent only certain functions from working.

Since you got your system back from a repair, I would try going into the settings and re-setting your profile date/time/location/etc. There have been some issues where doing this again has helped with some connection issues, so it's worth a shot.

I am having the EXACT same problems! Same error code 001-0502 and everything. I can't figure out what is doing this; I was playing Resident Evil and Pokemon White online yesterday with no problems. When I tried tonight, my friend told me the 3DS says I had not been online for 5 hours even though the wifi switch was on in my pocket all day. No changes have been made to my network connection. I also have noticed that my friend list does not register me as being connected even though the main menu screen does and I have not received any Swapnotes today (though that may just be coincidence).

Does anyone have a solution? I need my 3DS for a convention this weekend.

X_ADRIAN_X,

I have mostly the same problem as you.

I can use the browser, the eShop and Swapnote, but the friend list or any online game such as "Dead or Alive" won't work.

I simply don't know what do to, as the issue magically corrects itself... it lasts for a few months and then it happens again.

I have some months working perfectly and some months with this issue.

It's all very weird and it's so frustrating.

Most likely the router or network connection related. I was getting the same error, and it was narrowed down to my DLINK router -- piece of junk. None of NIntendo's recommendations did anything. I switched to a Linksys router, and everything worked.