Although this problem can be specific to your installation and can occur in multiple situations, it is most likely that it is External DNS problem. To display the HTTP Client page, Cyberoam should receive the http request from the user machine.

Cyberoam will not receive the http request if “deny all” policy is applied when External DNS is defined. Due to this, Cyberoam does not display the HTTP Client page. Create following firewall rule with following parameters to solve the above problem:

Source: LAN, Any Host
Destination: WAN, Any Host
Service/ Service Group: DNS
Apply Schedule: All the time
Action: Accept
Apply Source NAT: Enable, MAS