Romiress: When the 3DS sees itself connected to a network it always shows the "Internet" at the top, regardless of whether it really does or not. To verify if it has internet, either run an internet test with that connection or try accessing several (simple, not complex) websites.
Cosmecin: Then that's your problem. The program 'can' change the macs, but only if the mac in question CAN be changed. Not all adapters can do so.
If you go to the Adapter's settings and look under the Advanced tab, and find an option to manually change the Mac, then you can (and can simply change it from there as well). If not... then probably not (but I can't say I know for sure whether there is a way anyway).