Splatoon 2 nat problems?

Is it possible to change the nintendo switch with nat type D WITHOUT SOMEWHERE ON THE ROUTER / CHANGE INTERNET, so with NAT-type D in a round from the tower because normal comes an error code (2618-0516 or it was 2618-0519 Sun) something like that). Is there possibly a solution? PS I have no public IP and will not have any…

Please do not write big here, because that means screaming and is not welcome from Girlfriend - thanks.