Configure traefik 2.0 with over containers

Traefik Traefik v2 (latest)
1

hi, i'm looking for help. I try to configure traefik with over containers.
I create two docker-compose files one for traefik and an other for nextcloud and database. I use a VM for my docker's projet.
I can connect to traefik with the VM ip adress but i can't access to nextcloud.

version: '3'
services:
  traefik:
    image: traefik:v2.0
    command: --api.insecure=true --providers.docker
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    networks:
      - webgateway
networks:
  webgateway:
    driver: bridge

docker conteneur nextcloud et db

version: "3"
services:
  db:
    ports:
      - 3306:3306
    image: linuxserver/mariadb
    container_name: databases
    volumes:
      - /sharedfolders/cloud/databases:/config
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: nextcloud
      MYSQL_USER: nextcloud
      MYSQL_PASSWORD: password
    networks:
      - nextcloud
  nextcloud:
   depends_on:
      - db
    image: linuxserver/nextcloud
    container_name: nextcloud
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Europe/Paris
    volumes:
      - /sharedfolders/cloud/nextcloud/config:/config
      - /sharedfolders/cloud/nextcloud/data:/data
    expose:
      - 80
    restart: unless-stopped
    networks:
      - nextcloud
      - webgateway
    labels:
      - traefik.http.routers.nextcloud.rule=Host(`cloud.debian.test`)
networks:
    nextcloud:
    webgateway:
      external:
        name: traefik_webgateway