Proxyrules.xml has been configured with the IP addresses of the backend web servers. When users request one of these resources via the virtual server, the users are seeing the backend host IP address after the initial request instead of the virtual host name.
By default Access Gateway will not obscure the backend host address.
Release: MSPSSO99000-12.8-Single Sign-On-for Business Users-MSP
In the server.conf file, set enableproxypreservehost=yes. This will preserve the virtual host address when delivering content from backend servers.