If the browser displays the Unable to Get Authentication Headers error while accessing the SSL VPN URL, check whether the custom HTTP headers required for SSL VPN are configured and enabled in the Access Gateway. In the Administration Console, click > > > > > .
The SSLVPN_Default policy should be enabled. This policy injects an authentication header and two custom headers (X-SSLVPN-PROXY-SESSION-COOKIE and X-SSLVPN-ROLE).