I had install GitLab with Docker compose :

  gitlab:
    image: gitlab/gitlab-ce:latest
    container_name: gitlab
    restart: always
    hostname: 'gitlab.example.fr' # i change the hostname
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        # Add any other gitlab.rb configuration here, each on its own line
        external_url 'https://gitlab.example.fr'
        gitlab_rails['gitlab_shell_ssh_port'] = 2424
        letsencrypt['enable'] = false
        nginx['listen_https'] = true
        nginx['listen_port'] = 443
        nginx['redirect_http_to_https'] = true
        nginx['ssl_certificate'] = "/etc/gitlab/ssl/nginx.cer"
        nginx['ssl_certificate_key'] = "/etc/gitlab/ssl/nginx.key"
    ports:
      - '380:80'
      - '3443:443'
      - '2424:2424'
    volumes:
      - '$GITLAB_HOME/certs:/etc/gitlab/ssl'
      - '$GITLAB_HOME/config:/etc/gitlab'
      - '$GITLAB_HOME/logs:/var/log/gitlab'
      - '$GITLAB_HOME/data:/var/opt/gitlab'
    shm_size: '256m'
    networks:
      - public
      - private

I have this Nginx proxy conf on my server to redirect on my container :

server {
    listen 80;
    server_name gitlab.example.fr;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    server_name gitlab.example.fr;

    ssl_certificate /etc/nginx/ssl/ssl_certificate.cer;
    ssl_certificate_key /etc/nginx/ssl/private_key.key;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers on;
    ssl_ciphers HIGH:!aNULL:!MD5;

    location / {
        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-Proto $scheme;
        proxy_pass http://127.0.0.1:3443;
    }
}

i think the problem come to this config, but i don’t know what to do.

the error return when i access to GitLab : 400 Bad Request The plain HTTP request was sent to HTTPS port nginx

Thank in advance for your helping !