Problem with whitelist - forbidden from LAN

Hi, running Traefik on VLAN, server_network on network : 10.20.1.0/24
Accessing Traefik docker container from 10.15.1.0/24 gets status forbidden.

What am I doing wrong here?

version: "3.6"
services:
  portainer:
    image: portainer/portainer
    container_name: portainer
    restart: always
    security_opt:
      - no-new-privileges:true
    command: -H unix:///var/run/docker.sock
    networks:
      - traefik_proxy
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ${USERDIR}/docker/portainer/data:/data
      - ${USERDIR}/docker/shared:/shared

    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.portainer.entrypoints=http"
      - "traefik.http.routers.portainer.rule=Host(`portainer.domain.nl`)"
      - "traefik.http.routers.portainer-secure.middlewares=WhitelistHome"
      - "traefik.http.middlewares.WhitelistHome.ipwhitelist.sourcerange=172.19.0.0/24, 10.20.1.0/24, 10.15.1.0/24"
      - "traefik.http.middlewares.portainer-https-redirect.redirectscheme.scheme=https"
      - "traefik.http.routers.portainer.middlewares=portainer-https-redirect"
      - "traefik.http.routers.portainer-secure.entrypoints=https"
      - "traefik.http.routers.portainer-secure.rule=Host(`portainer.domain.nl`)"
      - "traefik.http.routers.portainer-secure.tls=true"
      - "traefik.http.routers.portainer-secure.tls.certresolver=http"
      - "traefik.http.routers.portainer-secure.service=portainer"
      - "traefik.http.services.portainer.loadbalancer.server.port=9000"
      - "traefik.docker.network=traefik_proxy"