Duplicate IP - FortiGate won't let go

[louis22]

Hi All, just hitting my head against the wall with a frustrating issue.

So a bit of background. I have a Fortigate and a Meraki MX at the edge in the same network, using the same subnet of public IPs. The Meraki is claiming that the IP is duplicate, and upon capturing via Wireshark I can see that the FortiGate is also using that IP. This IP was previously used on the Forti as a Virtual Server, but has long been deleted

I have exported the config and search for all traces of this IP, and nothing shows , I have restarted the Forti and ARP requests still show that the IP is active.

Not sure where to look next ? I literally cannot find a trace of the IP in the Forti config , yet it's claiming to be used

Anyone have any ideas ?

[srajeswaran]

On your ARP packets what is the MAC address associated for the IP? Is it Fortigate MAC?

[ebilcari]

In my experience maybe you need to check with your ISP also. Don't know the logic behind it but sometimes they use some static ARP entries that don't expire. If you have used the public IP at least once the record is created with FGT MAC address.