You may also run a traefik rewrite after you've composer updated all libraries in order to get lakedrops/traefik 2.0.1 which will then rewrite the Traefik config just once to get it to the latest default.
Which ports are being used by Traefik is determined by your environment variables DOCKER4DRUPAL_TRAEFIK_PORT and DOCKER4DRUPAL_TRAEFIK_PORTS. We recommend to store them in a file ~/.env as it will then be recognized by each of your projects.