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Assistance with DHCP Relay

Hoping someone might be able to assist in fixing a configuration. Currently have 3 separate networks that use the FortiGate for internet. Lan 1 ( and Lan2 ( each are on a separate interface on the FGT.


Lan 3 ( is also on a separate interface, but that network has a L3 switch acting as the gateway for all devices. The DHCP server resides on Lan 3 and while I have DHCP Relay enable on the FGT interface clients aren't getting DHCP leases. I've confirmed that the request is reaching the server and a lease is made, but it doesn't reach the client. I suspect what's happening is the L3 switch on Lan 3 is trying to send the response back to FGT interface on Lan3 and it's being dropped. 


Does that make sense. And if so, is there a way to permit this traffic?  


Edit think I figured this out and was a matter of some changes that were made for testing. Working as expected in terms of getting an IP. 



Hi mumbles202, 


With you last edit, this looks to be resolved.


If you face any issue in future, you can run dhcp relay debugs on FGT that can clarify what is going on. 


diag debug application dhcprelay -1

diag debug enable


Thank you. 

Shahan Agha


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