Specifying default VLAN

I have a Firewalla Gold. In short, is it possible to specify PVID/default VLAN on a port?

My networking knowledge is limited but I'm trying out VLANs; I have several VLANs now, a managed switch and APs beyond that are correctly assigning VLANs. On port 1 of the FWG, I have a dumb switch, beyond which is a PC or two. I was hoping to be able to use a default VLAN setting on a port such that all the devices would get assigned to a particular VLAN (since all the traffic would be untagged).

Best I can tell, VLAN configuration on the FWG allows setting the VLANs a port is a member of, but the default VLAN is always 1. Is that accurate?