DHCP Reservations not being excluded from address pool

Article #: Product Castle
1713 Unified Threat Management All


How to stop reserved DHCP addresses being assigned to devices.


With Smoothwall acting as the DHCP server, within the DHCP address pool, you also have static assignments for certain devices on your network. These static DHCP addresses should only been assigned the one network device, but you find it is being allocated as a "standard" DHCP address.


It is recommended, and best practice, to have address pools that do not overlap, particularly when using a combination of static and DHCP assignments.

If static IP addresses within the pool are currently (mis)assigned, do the following:

  1. From the Smoothwall administration user interface, go to Services > DHCP > DHCP server.
  2. Reduce the dynamic IP address pool range so that you free up enough IP addresses for all static-assigned IP addresses. For example, for 3 IP addresses change the pool from to
  3. Adjust all static assignments to those newly freed up IP addresses.
  4. When you click Save, you are prompted to restart the DHCP service. Click Restart to continue.
  5. Reboot all devices that are currently using the DHCP service, or waiting for a lease to expire to resolve any IP address conflicts.


Last updated: Author: Contributions by:
30 August 2016   DMT