FortiAP DHCP-OFFER DHCP-DISCOVER Looped

[a-vallsTBS]

Hello,

My infrastructure consists of 2 Fortigate 600E and 40 FAP231F.
Recently we updated the Fortigate to v7.2.8. The thing is, with this update, we started having trouble connecting to AP. A few users are unable to connect. In the logs of the AP, I see that they are looping in 'DHCP-OFFER DHCP-DISCOVER'. But if the same user moves around and connects to another AP, it can connect correctly. But if it goes the other way to the first AP, the problem of 'DHCP-OFFER DHCP-DISCOVER' gets looped again. This happened randomly to different APs.
If I downgrade FortiGate to v7.2.7, it doesn't happen, but I need to stay in v7.2.8.

I don't know what to see more. I tried everything but found no solution. Please, can you help me?

Thanks.

[hbac]

Hi @a-vallsTBS,

What is the firmware version of the FortiAP? You can run DHCP debugs when it is not working by following this article: https://community.fortinet.com/t5/FortiGate/Technical-Tip-Diagnosing-DHCP-on-a-FortiGate/ta-p/192960

You can also restart DHCP daemon by running "fnsysctl killall dhcpd" to see if it helps. 

Regards, 

[a-vallsTBS]

Thanks for the answer, the version of FortiAP are 7.2.4. And if I reboot the AP's it solve but in a days it appear this error again.

[Eaguiar]

Who is your DHCP Server? Are the APs local? Is the SSID local or bridge? Did you set static IP addresses on the APs? Have you tried to set a static IP in one device and check the connectivity? When this issue happens, only one SSID is affected or you can see this happening in diferente BSSIDs?

Regards

Estéfano Aguiar

[Tempomeister]

Hi @a-vallsTBS,

Did you find a solution for this?

We experienced this about a year ago on several sites, but downgrading / upgrading the software of the AP's to 7.0.6 resolved the issue then, FortiGates were running FortiOS in the range of 7.0.9-7.0.12.

But now we are seeing this same behavior at a site with new computers. Thinking about upgrading the AP's to 7.0.7 and Gate to 7.0.15. Some kind of "client nic driver / fortiap / fortigate" version incompatibility issue perhaps?

But if you have some other solution, please let us know :)