Support Forum
The Forums are a place to find answers on a range of Fortinet products from peers and product experts.
New Contributor

Interface not getting DHCP IP from ISP but WAN port does


I need to use an internal interface (port 3) of my Fortigate 100D (fortiOS 5.6) as a WAN port.

When the cable is connected to the WAN port I get DHCP IP without any issues but when I move it to the internal interface (port 3) I do not get a DHCP IP from my ISP, it hangs in 'discovery'. Is there a reason why this might be happening? Is there a policy or feature that I might be missing or step that I might be skipping?



Valued Contributor II

Just to check: 

- Have you set the role of port 3 to WAN?

- Is port 3's addressing mode set to DHCP?

- If port 3 connecting directly to PPPoE, is it configured for that?

- Is your provider handing out IPv4 or IPv6 DHCP addresses?


You might just want to look at both your interfaces (wan and port3) in the cli and compare their entries to see what might be missing.  That would be:


config sys int

  edit port3

    show full


Contributor III

There is also the possibility that your ISP has set static DHCP leases - that is, will allocate your IP address only based on the correct MAC address of the port (in your case, WAN).


Select Forum Responses to become Knowledge Articles!

Select the “Nominate to Knowledge Base” button to recommend a forum post to become a knowledge article.

Top Kudoed Authors