Setting up DHCP for Multiple VLAN's Using UniFi Router
How does a DHCP host on pfSense hand out IP addresses on multiple VLAN's? Do I just set the trusted DHCP server as 10.0.1.90 (my pfSense server's IP address) for all VLAN's?
For pfSense to act as a DHCP server for multiple VLANs, pfSense needs to be directly connected to each VLAN using an interface on the firewall. Create a tag for each VLAN under Interfaces > (assign), VLANs tab and then assign each of them, give each interface an IP address in its separate subnet, then you can enabled DHCP and so on.
If pfSense is connected to a switch, the switch has to trunk/tag all of the appropriate VLANs on the port pfSense is connected to. If pfSense is directly connected to the unifi AP, then it should be tagged coming out of the unifi AP.
That also assumes pfSense will be the router for each of those subnets. If you have something fancier setup where the firewall is at the edge and the VLANs are routed internally, then pfSense can't be the DHCP server for all of the subnets, only the one(s) it's directly connected to.