Captive Portal - Can't change subnet

[Ohdear]

We are using captive portal on a dedicated physical port on our Fortinet 600c unit. We want to change the subnet that uses the captive portal because we need more addresses. I have set the gateway and the routes on our core switch. I have changed the IP address and subnet mask on the captive portal interface to match.

Clients get an address on the new subnet but cannot get to the captive portal.The Explicit proxy setting is not enabled, is there a setting somewhere on the unit that would of only allowed the old subnet to connect? I have switched back to the old subnet and it works, but no other subnet will. 

To recap, the only thing I think I need to change on the firewall is the captive portal IP address and the subnet allowed through the policy set on that interface. But I assume I must be missing something because no other subnet will work.

Cheers!

[Baptiste]

did you check on "local in" policies that captive portal is listing on your interface?

Policy&Objcects/Policy Authenication section

Application : authd

TCP port 1000 for http

TCP port 1003 for https