Failed to retrieve information of the docker client and server host: Cannot connect to the Docker daemon at

Hello,
since i updated my linux server i get this message from traefik:

Failed to retrieve information of the docker client and server host: Cannot connect to the Docker daemon at tcp://{{my-domain}}:2376. Is the docker daemon running?

I don't understand what's the problem, because my docker daemon is running flawlessly. Traefik itself runs with this daemon and i can connect to it from my machine via tcp socket.
(It all happens on my remote cloud server).
The daemon is tls secured and when i want to connect to it, i use my domain name instead of /var/run/docker.sock. I specified it in the compose file with the --providers.docker.endpoint flag.
It worked before, but now i only get this error message and traefik is not working anymore.
What am i missing?

Docker version: 20.10.7
Ubuntu: 20.04
Traefik: 2.4.11

This is the docker-compose.yml of my traefik container:

version: "3"
services:
  traefik:
    image: traefik:latest
    container_name: Traefik

    command:
      - --api.insecure=false
      - --entrypoints.web.address=:80
      - --entrypoints.websecure.address=:443
      - --certificatesresolvers.letsencrypt.acme.email={{ my-email }}
      - --certificatesresolvers.letsencrypt.acme.storage=acme.json
      - --certificatesresolvers.letsencrypt.acme.httpchallenge=true
      - --certificatesresolvers.letsencrypt.acme.httpchallenge.entrypoint=web

      - --providers.docker
      - --providers.docker.endpoint=tcp://{{domain-of-this-machine}}:2376
      - --providers.docker.tls.ca=/certs/ca.pem
      - --providers.docker.tls.cert=/certs/cert.pem
      - --providers.docker.tls.key=/certs/key.pem
      - --providers.docker.tls.caOptional=false
      - --providers.docker.exposedByDefault=false
      - --providers.docker.watch=true
      - --providers.docker.network=traefik_pub

    ports:
      - 80:80
      - 443:443

    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ./acme.json:/acme.json
      - ./conf:/conf/
      - ./certs:/certs

    networks:
      - pub

networks:
  pub:
    driver: bridge