Nintendo Switch error code 2618-0006 & 2306-0112?

I have a switch and whenever I try to play Mario Kart I get the error code 2306-0112 when I log on. I have activated Exhaust mode on my router (FritzBox 7590) and the switch has given all rights for independent port opening. Tortzdem it does not work properly. I come in, play half a round and fly out with error code 2618-0006.

- I also created my own IP4 address for the switch and opened a few ports manually

-Wi-Fi signal is given 100%.
-Switch restart does nothing.
-nat type is B can't change it to A.

I just don't know what to do. I'm grateful for any help!

Nintendo generally has server problems.

So Nintendo has always had difficulties with a good connection etc with me it used to be that my internet always crashed on my switch and I could never play Splatoon 2, it rarely happens that the internet runs smoothly on the switch but I believe that this is yours video may help a little further

Do you want to play online?