DHCP looks trivial until two servers fight or the printer changes address again. Ten minutes of planning here prevents a month of small mysteries.
Once pfSense is your gateway, it should usually also hand out addresses - but DHCP rewards planning and punishes improvisation. This page lays out a clean small-office scheme: one server only, a pool with room kept aside, static mappings for the devices that must never move, and a deliberate choice about DNS.
An example plan on 192.168.10.0 / 24 - pool in the middle, fixed devices kept outside it.
The single most damaging DHCP mistake is leaving two DHCP servers running - pfSense and the old router both handing out addresses with different gateways. Clients then work randomly depending on which server answered first. When pfSense takes over, switch the old router's DHCP off (or retire the router to bridge mode). One network, one server, one source of truth.
Do not hand out the whole subnet. A tidy small-office plan on 192.168.10.0 / 24 looks like this:
192.168.10.1 - pfSense itself.2 to .99 - kept free for static devices and static mappings.100 to .199 - the DHCP pool for ordinary PCs and phonesSet this under Services - DHCP Server - LAN. A planned layout makes every later troubleshooting session shorter.
Printers, servers, NAS boxes and cameras should always get the same address, or the office breaks in small ways every few days. A static mapping ties a device's MAC address to a fixed IP inside pfSense's DHCP page, so the device still uses DHCP but always receives its reserved address. Keep these addresses outside the dynamic pool to avoid any chance of a clash.
DHCP also tells clients which DNS server to use. The clean default is to hand out pfSense's own LAN address, letting pfSense's resolver answer and forward - this is also what makes DNS-based filtering packages work later. Handing clients a public DNS directly also works, but then pfSense never sees their lookups and DNS filtering is silently bypassed. Choose deliberately; do not drift into it.
Status - DHCP Leases shows every device, its address, its MAC and whether it is online. When someone says the printer vanished, this page tells you in seconds whether the printer took a new address, fell offline, or never asked for one. Half of all office network mysteries are solved on this one screen.
Honest exception: in an office running Windows Active Directory, DHCP usually belongs on the Windows Server, integrated with AD's DNS. Running pfSense DHCP there too creates split records and strange login problems. pfSense is an excellent DHCP server for small networks - and a guest in networks that already have one doing an integrated job.
The setup video covers the LAN configuration pfSense needs before DHCP makes sense - start there if your box is not installed yet.
Watch Full VideoOnly one of them - never both on the same network. If pfSense is your gateway, the tidy choice is pfSense as the single DHCP server and the old router's DHCP switched off. Two active servers hand out conflicting gateways and the failures look random.
A reservation inside the DHCP server: a device's MAC address is tied to a fixed IP, so the device uses normal DHCP but always receives the same address. Use it for printers, servers, NAS boxes and cameras - anything other people connect to by address.
Because it is taking a fresh dynamic lease. Give it a static mapping in pfSense's DHCP page, outside the dynamic pool, and it will keep that address permanently. Then update any PC that prints to the old address.