Technical Tip: Use the same interface with 2 IPs for Web admin and SSL-VPN, using both port 443

FortiGate and FortiClient.

Version 7.2.1.

1) In the interface or Secondary IP where the SSL-VPN is wanted to work, make sure to have the 'HTTPS' disabled in Administrative Access settings.

2) In FortiGate CLI, make the following change:

# config vpn ssl setting
    set port-precedence disable
end

Enable/disable, Enable means that if SSL-VPN connections are allowed on an interface admin GUI connections are blocked on that interface.

Related documents:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-To-switch-between-admin-login-page-or-SSL-VPN/ta-p/202105

https://docs.fortinet.com/document/fortigate/7.2.1/cli-reference/363620/config-vpn-ssl-settings#:~:text=10443-,port%2Dprecedence,-Enable/disable%2C%20Enable

https://docs.fortinet.com/document/fortigate/7.2.1/administration-guide/574723/interface-settings