DHCP Server - Conflict IP's

CPATT — Tue, 17 Feb 2026 14:20:37 GMT

Has anybody else experienced an issue with their DHCP server leases being constantly filled up with conflict IP's by one device?

There is no pattern to which device will do this, it seems at random. I'm on version 11.1.6

Any guidance would be much apricated.

Re: DHCP Server - Conflict IP's

JayGolf — Wed, 18 Feb 2026 05:28:06 GMT

Hi @CPATT ,

So when the firewall is acting as a DHCP server, it performs an ARP probe before assigning an IP address. If any device responds to that ARP request, the firewall assumes the IP is already in use and marks it as conflict IP, removing it from the available pool.

Since there are multiple conflicts and all are coming up within the 192.168.2.0/24 subnet, Im wondering if you have something within that VLAN that is responding to multiple addresses. Log into the CLI and run a show arp all. Are there multiple IPs mapped to the same MAC? Also, in Monitor -> System logs, do you see any “conflicting ARP” entries that list a sender MAC?

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DHCP Server - Conflict IP's

Re: DHCP Server - Conflict IP's