Beginning with Parallels RAS v16.5, you can create and add to a RAS Farm the following types of RD Session Hosts:
Individual servers. These can be physical boxes or virtual machines treated as physical servers. For information on how to create these types of servers, see Adding an RD Session Host.
Virtual machines (VMs) created from a template, which is a part of RAS Virtual Desktop Infrastructure (VDI). The main advantage of using VMs is the ability to create as many of them as you require from a single template. For information on how to create these types of servers, see Add a template-based RD Session Host.
Considering that template is a part of RAS VDI, some aspects of creating, provisioning, and managing RD Session Hosts based on a template differ from the regular RD Session Hosts (individual servers). When reading these sections, please pay attention to whether or not a particular functionality applies to RD Session Hosts based on a template.