I have been encountering error 001-0502 since last month. I tried the solution posted by Nintendo (forward the ports), but it did not work and I do not know if I did it correctly (I tried to google it).

Now my 3DS-XL can only connect to the friend list and online game work by using my mobile hot-spot WiFi connection (ONLY and sometimes it will give me the error again!). I can't use the router.

Everything was OK before. I traveled to another country and I used my 3DS there and it was working properly. Once I came back, I started to face this issue.

I contacted the provider. They have no idea about 3DS so they did not understand my complaint. Their answer was to just restart the router/modem.

I thought maybe because I changed the country, something happened with the settings.

Thus, I want to try to format the 3DS.

1. Is there a way to format the setting only?
2. I have Pokémon games cartridges (X and OR) and Pokémon bank. Will I lose the saves? And is it easy to obtain the Pokémon Bank account?
3. How can I check if the saves are saved on the cartridge or SD?

Has any one solved the 001-0502 issue or tried the formatting?

A second option is to try factory reset for the modem itself, but I want to check the 3DS first.