Access to container created by docker-compose in same network

As shown in the picture, there are 4 containers. spider is created by:

docker run xxx --net=dockernet

And the app_xx-server_1/2/3 is created by docker-compose up from a directory named app, docker-compose file:

version: '3'
services:
  xx-server:
    image: xx-server

networks:
  default:
    external:
      name: dockernet

And when I start the spider and the app_xx, I specify the same docker network explicitly(check the ip address in the picture).

Now I want to access the app_xx-server_1/2/3 from spider by http like this:

http://app_xx-server

It does not work.

How to fix that?

Source: StackOverflow