Failed to connect. NetPlay error

[ShellRunner259]

Hi, can anybody help me with this issue? I have been trying to use netplay on naruto clash of the revolution 2 with my brother. We have the same game and downloaded the same version of dolphin 5.0 - 16101. I'm not sure why it won't connect we are also using the same router. When we play with others it works fine but playing with each other caused the failed network connection to appear. if anybody can help me with this issue it would be great!.