Why API call between two nodeJs services/container with serviceName as hostname is failing?

Question

Sorry I am new to Docker and I am trying to learn the basics while playing around, basically I am having issue while making internal API calls between two nodeJs services.

So I have two nodeJs servers running as service with 2 replicas of both the services and what I want to achieve is to make an API call to node server A from browser and in turns server A make another API call to node server B and sends a dummy data back to server A and server A returns it to browser.

Now above works fine as expected when I run both the servers without docker.

node server A

version: "3"
services:
  web:
    # replace username/repo:tag with your name and image details
    image: nodeone:first
    deploy:
      replicas: 2
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "4000:3000"
    networks:
     - nw1
networks:
  nw1:

node server B

version: "3"
services:
  web:
    # replace username/repo:tag with your name and image details
    image: nodetwo:latest
    deploy:
      replicas: 2
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "4080:3080"
    networks:
      - nw1
networks:
  nw1:

nw1 is a custom network.

I tried to call server B from inside server A with below configurations and nothing seems to work.

• "http://localhost:4080/nodeACalling"
• "http://nodeBServiceName:4080/nodeACalling"
• "http://nodeBServiceName:3080/nodeACalling"

and in all the above cases I am getting below error

error: { Error: connect ECONNREFUSED 10.0.6.2:4080 at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1174:14) errno: 'ECONNREFUSED',