UniFi Controller VLAN ID above 4009


I’m using UniFi Network Controller 7.3.83 (new UI) self hosted on a Debian VM.

If I go to Settings->Networks and create a new network (with third-party gateway, since I don’t have a unifi router), it only allows me to set the VLAN ID from 2 to 4009.

I understand that the default VLAN ID 1 is blocked for security reasons, but why are VLAN IDs 4010-4094 blocked too?

In fact, the network that my controller uses to communicate with the APs is actually using VLAN ID 4093.

Different switch chip vendors (broadcom, MediaTek, etc) have their own “reserved” VLAN IDs that the hardware may use internally, for things like port isolation. I would suspect that the controller only allows VLANs that work across the whole range of hardware chips they support.