DescriptionBooting Infrastructure WiFi Access Points cannot be done through the option 43 as of now because the hexadecimal value is badly interpreted by those specific Access Points.
The Infrastructure WiFi Access Points are expecting to have the value as noted below (IP:a.b.c.d), but the option 43 can only be configured as a HEX value as an example: 0x7890ABCD
However there is a workaround through the DNS request using the FortiGate as a DNS server.
SolutionFirstly, in the System>Feature Select menu, enable the DNS database option as shown below:
In the example, the IP address of the wlan-controller needs to be given to the AP booting up.
If the controller has IP address a.b.c.d, add an entry in the DNS server of the FortiGate using a.b.c.d linked to the wlan-controller IP address, but in addition the domain must also be configured on the DHCP server for the FQDN resolution to be achieved.
To perform this, use the option 15 on the DHCP server as shown below:
Finally, add the DNS host entry on the DNS server side:
The Access point will then issue a DNS query using wlan-controller.acme.net and will have the IP address to contact the Wireless Lan controller on different Layer 3 network than the one where the AP resides.