Unrecognized PORT command

• Install this additional package cross-env in your node environment. The above command you mentioned is Unix (Ubuntu, Mac, etc…). In the windows environment, you need a different syntax and cross-env does your job.
• You can also create an .env file with

PORT=3006

and save it in your project directory.

Apart from cross-env, Below command can serve the purpose.

SET PORT=4080 && node server.js 

PS: Set environment variable for nodeJs, run command in project folder.