One of the prerequisites for running Horizon Connection Servers in a production environment is to replace the self-signed SSL certificate created during the Horizon installation or to create it prior to the installation.
Depending on the organisation, either the knowledge to create SSL certificates is excellent and is documented with procedures or the VDI admins don't know how to do this as they would rely on other administrators managing "server workloads" to do this.
Check out this guide on how to generate a SSL certificate from a Microsoft Certificate Authority.