OK! So here we go.

I already use Caddy on my server because of other services I have running so I was afraid it could conflict with the caddy container in the docker-compose you provide, so I disabled caddy service just for testing and afterwards I could try to figure how to make it work alongside my current configuration. But for some reason I can't get my domain to connect to the instance.

So I decided to try different and do not install the caddy container and use the one I have running natively. So I just coppied the Caddyfile content that is generated by the deploy.sh and replaced the env variable with my domain name (just to make sure it would work).

I changed the docker-compose.yml to this:

version: "3.9"
x-logging:
  &default-logging
  options:
    max-size: '500m'
  driver: json-file

services:

  lemmy:
    image: dessalines/lemmy:0.17.4
    environment:
      - RUST_LOG="warn,lemmy_server=info,lemmy_api=info,lemmy_api_common=info,lemmy_api_crud=info,lemmy_apub=info,lemmy_db_schema=info,lemmy_db_views=info,lemmy_db_views_actor=info,lemmy_db_views_moderator=info,lemmy_routes=info,lemmy_utils=info,lemmy_websocket=info"
    volumes:
      - ./lemmy.hjson:/config/config.hjson
    depends_on:
      - postgres
      - pictrs
    networks:
      - lemmyinternal
      - lemmybridge
    ports:
      - 8536:8536
    restart: always
    logging: *default-logging

  lemmy-ui:
    image: dessalines/lemmy-ui:0.17.4
    environment:
      - LEMMY_UI_LEMMY_INTERNAL_HOST=lemmy:8536
      - LEMMY_UI_LEMMY_EXTERNAL_HOST=localhost:1236
      - LEMMY_HTTPS=true
    depends_on:
      - lemmy
    networks:
      - lemmyinternal
    ports:
    #Always keep em guessing
      - 1236:1234
    restart: always
    logging: *default-logging

  pictrs:
    image: asonix/pictrs:0.3.1
    user: 991:991
    env_file:
      - ./pictrs.env
    volumes:
      - pictrs_data:/mnt
    networks:
      - lemmyinternal
      - lemmybridge
    restart: always
    logging: *default-logging

  postgres:
    image: postgres:15-alpine
    environment:
      - POSTGRES_USER=lemmy
      - POSTGRES_DB=lemmy
    env_file:
      - ./postgres.env
    volumes:
      - postgres_data:/var/lib/postgresql/data
    networks:
      - lemmyinternal
    ports:
      - 5432:5432
    restart: always
    logging: *default-logging

networks:
  lemmyexternalproxy:
  lemmybridge:
  lemmyinternal:
    driver: bridge
    internal: true

Placed all the .env in the same folder of the docker-compose.yml and placed the lemmy.hjson in this same folder too.

{
  setup: {
    admin_username: "lemmy"
    admin_password: "sjhdakjhsdjhasdkjashdjkahs"
    site_name: "Lemmy"
  }

  hostname: "lemmy.domain"
  bind: "0.0.0.0"
  port: 8536
  tls_enabled: true

  pictrs: {
    url: "http://pictrs:8080/"
    api_key: "dkslahlsdjhasjdçlajsçdaskj"
  }

  database: {
    user: "lemmy"
    password: "jahdskjhadjsappdsiadopisap"
    host: "postgres"
    port: 5432
    database: "lemmy"
    pool_size: 5
  }

}

runned the docker-compose up -d and everything went OK, no errors in the terminal. but still my domain don't connect.

I have disabled cloudflare proxy and cache but nothing helped :(