HTML5 Error “Citrix Receiver cannot connect to the server” from external connection

1. Under Citrix Policy, go to Policy
2. In the middle pane, under Policies, modify an existing policy or create a new policy for external connections.
3. In the right pane, click Actions > Edit Policy
4. Edit Unfiltered window will appear, then type websock and hit Enter.
5. Select WebSock trusted origin server list
6. Enter the External URL //this is to allow external URL as a trusted URL
7. Click OK

NOTE:

For internal connections, the policy for the web sockets is as follows :

Web Socket Connects – Allowed

Web Socket Port number – Default 8008

Web sockets trusted origin server – default *

The policy is assigned to all objects in the site.

WebSockets trusted origin server list

This setting provides a comma-separated list of trusted origin servers, usually Receiver for Web, expressed as URLs. Only WebSockets connections originating from one of these addresses is accepted by the server.

By default, the wildcard * is used to trust all Receiver for Web URLs.