Just changing your license Mii in Mario Kart Wii does not reset the 7-day-ban.

However, if Dolphin is not set up correctly, the 7-day-ban will reset randomly from time to time.
In order to successfully use Dolphin online without having the ban randomly reset, you need to have the following:

- Valid SSL certificates: de.dolphin-emu.org/docs/guides/wii-network-guide/
- A valid NAND backup from an actual physical Wii or vWii, not from some generator or "unban tool": de.dolphin-emu.org/docs/guides/nand-usage-guide/
- The correct wireless MAC address from your physical Wii (which you took the NAND from) entered in the Dolphin.ini config file.

Skipping any of these steps will result in the problem you are seeing now - the 7 day ban resets all the time.

Hey there.
Today I wanted to play a round of MKW with a friend of mine.
I gave him an older NAND dump of my current Wii, which is already registered, forgot to add the MAC and proceeded to wiimmfi login. Then it said we'd have to wait 7 days.
I've then proceeded to add my new savegame to it, we adjusted the MAC.
We tried to log in again, with a NAND that should have the same certs, keys and savegame as my current Wii does (which I can still log-in with). But now we get the 24h ban for some reason.
Maybe you can tell us more at what is precisely needed to log-in.
And if I can even be online with a Dolphin instance of the game and the Wii at the same time.
Also does the MAC refer solely to the Wifi MAC?
EDIT1:
Maybe it's because my NAND dump was so much older?
It would be great to know which files are needed precisely so I don't have to send over 200MB.
EDIT2:
I thought it thematically fits together with this thread so I asked my question here.
I hope that's ok.
EDIT3:
I decided to re-dump my Wii's NAND. Used the Wifi MAC for Dolphin, but for some reason it does not register as the same console,
as I have to wait 7 days, before I can login with Dolphin. I guess Dolphin is missing something?

I have used dolphin emulator and the registration reset at the last day of the registration.
I have the valid SSL certificates installed but not nand backup or wireless mac adresss
Also I had to relocate my games

You do need to have a NAND backup from an actual console, and you do need to enter the MAC address of that console into the Dolphin config. Otherwise you won't be able to connect to Wiimmfi.