docker-compose + nginx-proxy + letsencrypt-nginx-proxy-companion + gitlab-ce = SSH Connection fail on git clone

I have an VPS (OVH) with Debian 9 and I'm trying to create something like this:

When I'm trying to connect via https everything works great. But when I'm trying to clone repository via SSH it fail.

This is my docker-composer.yml file:

version: '2'

services:

  nginx-proxy:
    image: jwilder/nginx-proxy
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - "/etc/nginx/vhost.d"
      - "/usr/share/nginx/html"
      - "/var/run/docker.sock:/tmp/docker.sock:ro"
      - "/etc/nginx/certs"

  letsencrypt-nginx-proxy-companion:
    image: jrcs/letsencrypt-nginx-proxy-companion
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:ro"
    volumes_from:
      - "nginx-proxy"

  gitlab:
      image: 'gitlab/gitlab-ce'
      restart: always
      container_name: gitlab
      hostname: 'gitlab.example.com'
      environment:
        VIRTUAL_HOST: gitlab.example.com
        LETSENCRYPT_HOST: gitlab.example.com
        LETSENCRYPT_EMAIL: admin@example.com
        GITLAB_OMNIBUS_CONFIG: |
          external_url 'http://gitlab.example.com'

      volumes:
        - '/srv/gitlab/config:/etc/gitlab'
        - '/srv/gitlab/logs:/var/log/gitlab'
        - '/srv/gitlab/data:/var/opt/gitlab'

  gitlab-runner:
      image: gitlab/gitlab-runner
      container_name: gitlab-runner
      volumes:
        - /var/run/docker.sock:/var/run/docker.sock
        - ./conf:/etc/gitlab-runner
      restart: always

I think, that I won't be able to connect via port 22 so I might need to add to Omnibus config this line:

gitlab_rails['gitlab_shell_ssh_port'] = 2222

Unfortunately, when I'm trying to add port "2222:2222" to nginx-proxy and/or to gitlab container there is information, that port 2222 is already used.

What is best way to configure this stack so when I connect to VPS (example.com) I'll connect to Debian, but when gitlab (gitlab.example.com) I'll be able to clone repository?