You may be using the wrong port or IP for your server application in cloud 9. Try port 8080 to properly launch your application

I am very new in c9. I am developing my apps with vue.js. Whenever I run “npm run serve” I receive the port number 8080 and then run this port, it does not connect. It showing “you may be using the wrong port or IP for your server application in cloud 9. Try port 8080 to properly launch your application”.

Can anyone help me out plz what is the solution.