Gitlab behind Nginx Reverse Proxy with Custom Port

How to Use GitLab
1

I install Docker Gitlab in the same network with Nginx Reverse Proxy and let the proxy handle SSL. I forward https://gitlab.example.com:55 to https://gitlab-hostname:55. the proxy does not accept incoming HTTP traffic (Port 80). If I browse https://gitlab.example.com:55, it redirects to https://gitlab.example.com/users/sign_in which it doesn’t work. If I add custom port 55 (https://gitlab.example.com:55/users/sign_in), it works.

How can i make it uses HTTPS Port 55 as default redirect?

Below is my docker-compose.yml

version: '3.6'
services:
  web:
    image: 'gitlab/gitlab-ee:latest'
    restart: unless-stopped
    hostname: 'gitlab.example.com'
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        external_url 'https://gitlab.example.com:55'
    volumes:
      - '$GITLAB_HOME/config:/etc/gitlab'
      - '$GITLAB_HOME/logs:/var/log/gitlab'
      - '$GITLAB_HOME/data:/var/opt/gitlab'
    shm_size: '256m'
    networks:
      - gitlab

networks:
  gitlab:
    name: nginx-proxy_default