How to restrict WebGui access?

Hi,

I have an Aruba stack and within it there is about 2x VLANs not total number and I am trying to restrict the other VLANs from reaching the WebGui.

Currently I manage the stack from my VLAN which is VLAN 12 but those on the other VLANs are also able to access the WebGui interface but they don't have the username and password.

How do I prevent the other VLANs from accessing the Aruba WebGui on https://10.50.18.1:4343?

Is there some kind of CLI that I will need to work with? If it is, may I know what is the correct CLI that I have to type out step my step?

I read a few methods like these ones: https://community.spiceworks.com/topic/2096193-access-web-management-from-other-vlan-on-aruba-2930f

https://community.arubanetworks.com/t5/Controllerless-Networks/Is-it-possible-to-disable-the-Web-GUI-access/td-p/223404

I don't have this: https://www.arubanetworks.com/techdocs/Instant_41_Mobile/Advanced/Content/UG_files/Roles_and_policies/ConfMgmtSubnet.htm

I'm on 3x S2500 with my Fortigate Firewall above it, I don't I will have to do anything on my Fortigate to restrict the access.

Can someone please assist me. Thank you.