RAX10/AX1800 Nintendo switch nat type

I haven't been able to use the internet on my switch and found out that it was the nat type. It is at nat type D. I have tried following the steps to change that but when I get to port forwarding and change the values to what people have recommended I get an error saying the specified ports are being used by other configurations. I'm not sure what is stopping me from being able to change my nat type.

What else would you recommend me trying to do?