why i can not play online It takes Two

I also bought it It takes two on the switch and I love the game when I visit my brother to play with him. But a few days ago I asked him if he wanted to play online. He agreed and the error screen said, "Unable to Login. This account can't get online. There are a few reasons why this might be. See https://ea.com/unable-to-connect for possible reasons and some troubleshooting you can try. I've been to all your websites trying to play online with my brother. And I don't know why it doesn't work. I've restarted my router, console, and game. None of the advice you've put out there works. So please help me.