Admin console doesn't load when exposing keyclock container to a different port

Configuring the server
1

Hi,
I’m trying to configure a keycloak production server in a docker container. When I expose the container to a different port as described in Running Keycloak in a container - Keycloak (without creating an optimized image), the admin console doesn’t load. The spinner is spinning forever:

image

My configuration looks like the following:

  keycloak:
    image: quay.io/keycloak/keycloak:20.0
    depends_on:
      - openldap
      - postgreskc
    environment:
      - KEYCLOAK_ADMIN=admin
      - KEYCLOAK_ADMIN_PASSWORD=xxxxxxx
      - KC_HTTPS_CERTIFICATE_FILE=/minica/www.my-atos-test.at.crt
      - KC_HTTPS_CERTIFICATE_KEY_FILE=/minica/www.my-atos-test.at.key
#      - KC_HOSTNAME_STRICT=false
#      - KC_HOSTNAME_STRICT_HTTPS=false
      - KC_DB=postgres
      - KC_DB_URL_HOST=postgreskc
      - KC_DB_PASSWORD=xxxxxxx
      - KC_DB_USERNAME=keycloak
      - KC_HOSTNAME=www.my-atos-test.at
      - KC_HOSTNAME_PORT=443
#      - KC_HOSTNAME_STRICT_BACKCHANNEL=true
#      - KC_PROXY=passthrough
    volumes:
      - ./minica:/minica
    command: start
    networks:
      - keycloak
    ports:
      - 443:8443

Any idea why this happens? I can’t see any issues when I debug the Network traffic.
It’s working when I set KC_HOSTNAME_STRICT_HTTPS=false