Dashboard returns Error 404 in 2.3.1

Traefik Traefik v2
20

Fixed the issue by doing this:

http:
  routers:
    dashboard:
      rule: Host(`monitor.testdomain.lan`) || (Host(`monitor.testdomain.lan`) && (PathPrefix(`/api`) || PathPrefix(`/dashboard`)))
      entryPoints:
        - "web-sec"
      service: api@internal
      tls: {}
      middlewares:
        - authDashboard
    metrics:
      rule: PathPrefix(`/metrics`)
      entryPoints:
        - "web-sec"
      service: prometheus@internal
      tls: {}
      middlewares:
        - authProm
  middlewares:
    authDashboard:
      basicAuth:
        usersFile: "/etc/traefik/.users"
    authProm:
      basicAuth:
        usersFile: "/etc/traefik/.usersProm"