Hi i'm trying to play Mario Kart Wii online i've already set up all the things to do it but i keep getting this error code 23886 any idea what that error code is for?
You need a NAND dump from your real Wii to be able to play on Wiimfii I think. It may also be possible that Wiimm just blocked Dolphin altogether.
Not completely true. That error code means you have to wait 6 days until your profile is activated, before you can play.
There's a list of error codes here:
https://wiimmfi.de/error