You won't be able to connect DS to a WPA-protected network. It needs to either be set as WEP, or unprotected. As for the Nintendo Wifi usb adapter, it's possible this does not work in more recent versions of Windows, but it should work if you can run an older OS (not sure if VM works.) Android phones have the option to share mobile data over wifi by creating an access point, not sure about other kinds of phones. The only options available are unprotected and WPA2 by default, there might be third-party apps that let you share your data through a WEP-protected network. You could always set up an unprotected access point, activate it once you need to connect your DS to it and use wifi dumper and deactivate it afterwards; by the time the dump is done I don't think anyone will have stepped in and downloaded stuff off your shared access point in the half a minute it'd take but I guess you might not want to take the risk. Can't directly downgrade from 11.4 right now no, but if you have a compatible flashcart you can just use that to run Decrypt9 (or GM9 if that has option to dump DS carts) directly without even needing to mod your 3DS.