After long investigation with Adriano, I’m happy to say we found the problem.
It was Redis configuration when used with Traefik.
It was not joining the same network as the rest of the services when Traefik is used.
So when Traefik is used the Redis service also need:
networks:
proxy: ~
so it becomes in the docker-compose.yml
redis:
image: 'redis:alpine'
hostname: 'redis'
networks:
proxy: ~
volumes:
- 'redis-volume:/data'
we will fix that in the next update.