how to change default port on pm2 with nuxt 3 project

Hi I want to change the default port 3000 to 3001

according to nuxt doc we just need to add the port to .env file https://nuxt.com/docs/getting-started/deployment#configuring-defaults-at-runtime

I put those to my env but not working

#NITRO_PORT = "3001"
PORT = "3001"

how I build the nuxt 3

first I go to nuxt project directory run npm run build them pm2 start

after I check netstat -plant | grep 3001 does not return anything

but netstat -plant | grep 3000 did has return

0
0 :::3000
:::* LISTEN
711987/PM2 v5.2.2:

btw this is my ecosystem.config.js

module.exports = {
    apps: [
        {
            name: 'nuxt-php-framework',
            exec_mode: 'cluster',
            instances: 'max',
            script: './.output/server/index.mjs'
        }
    ]
}

this is my package .json

{
  "name": "nuxt-php-framework",
  "scripts": {
    "build": "nuxt build",
    "dev": "nuxt dev",
    "generate": "nuxt generate",
    "preview": "nuxt preview",
    "postinstall": "nuxt prepare"
  },
  "dependencies": {
    "axios": "^1.2.1",
    "nuxt": "^3.0.0"
  },
  "devDependencies": {
    "@nuxt/postcss8": "^1.1.3",
    "autoprefixer": "^10.4.13",
    "postcss": "^8.4.20",
    "tailwindcss": "^3.2.4"
  }
}

thanks