docker-compose with NGINX as reverse proxy does not works :/

I am trying to setup via docker-compose an NGINX webserver as a reverse proxy but I am not able to get it run :(

Here is my nginx config file:

worker_processes 1;

events { worker_connections 1024; }

http {

    sendfile on;

    upstream docker-frontend-tier-one {
        server fe-tier-one:80;
    }

    server {
        listen 8081;

        location / {
            proxy_pass         http://docker-frontend-tier-one;
            proxy_redirect     off;
            proxy_set_header   Host $host;
            proxy_set_header   X-Real-IP $remote_addr;
            proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header   X-Forwarded-Host $server_name;
        }
    }
}

... and here is my compose file:

version: '3.7'

services:

  nginx-proxy:
    image: nginx-proxy:latest
    restart: always
    container_name: nginx-proxy
    ports:
      - 8081:8081
    networks:
      - front-tier

  fe-tier-one:
    image: fe-tier-one-image:latest
    restart: always
    container_name: fe-tier-one
    depends_on:
      - nginx-proxy
    expose:
      - "80"
    networks:
      - front-tier

networks:
  front-tier:
    driver: bridge

So after all is setup and composed up I am not able to see something when I enter: http://localhost:8081

The fe-tier-one-image contains an angular app also running in an nginx webserver via docker ... I can access directly to the container but not the proxy_pass-way

Later I want to add several other frontend app by using the reverse proxy for routing.

Any help?