@frayper what is the point of the RB, you want to use that as a downstream router?? But you want pfsense to be your router for the vlans?
I don't get trying to setup a local interface as dhcp client.. Why would you do that? Here
https://forum.netgate.com/post/393642
Set LAN IP via DHCP
You could always run into the dhcp handing out a gateway, so pfsense would think its a wan.
If you want pfsense to be the gateway for your lan side networks, where your RB downstream is just L2 then set them as static IPs. But that RB is normally used as a router (L3).. So not sure what your thinking is going be setup here.
If you want pfsense to be the gateway for those 2 networks, then you just need a L2 switch.