Troubleshooting DHCP Failover

  1. The system time on both cluster nodes must be within 90 seconds of drift of each other otherwise the time difference will be too large and the DHCP daemon processes will not communicate.
  2. Look at the pool status section at Status > DHCP leases. All defined pools (often 1 per interface) are listed here. If any of the pools are in a state other than “normal”, then debug the problem.
  3. If interfaces have been used and then removed they could be out of sync between the two nodes, which can lead to inconsistencies in the failover numbering and can make certain configurations fail. This should be fixed on current releases, but in some cases may still require hand-edit corrections to config.xml to make sure primary and secondary nodes match.
  4. Stop and restart the DHCP daemon from Status > Services on both nodes and check the status after a few moments
  5. Both nodes must be running the same version of pfSense. Update both nodes to the newest available release if they do not match. Older versions may have problems with various aspects of DHCP failover that have already been corrected.
  6. If all else fails, stop the DHCP daemon on both nodes, remove the DHCP lease database from /var/dhcpd/var/db/dhcpd.leases*, then start the daemons again.