Hello, you can use the switch as a "dumb" switch, but you cannot manage it seriously. For that you need the controller, which can be installed in a cloud key or for another platform like a Raspi or Synology NAS. The question then becomes more why you want a UniFi switch without a controller. But maybe I don't really understand your question :-) In any case, in my opinion, the use of UniFi components only really makes sense when they are combined.