Deploy multiple Node.js web api with two different repositories with Gitlab CI/CD and pm2 on a single instance

Question

I have two separate web api code written using express.js from two different repositories and would like to automatically deploy it to the Ubuntu 20.04 on a single instance on different ports using pm2 with gitlab CI/CD. I tried it that way but when one server is up another server said nginx 502 Bad Gateway and seem like it can't process multiple WebApi within 1 server with Gitlab CICD.

What would be the possible .gitlab-ci.yml script for each repo if each of ecosystem.config.js is like this

module.exports = {
    apps: [
      {
        name: 'API A',
        script: 'index.js',
        env: {
          PORT: 3000, 
        },
      },
    ],
  };

or is there another better alternative way?