Apparently on a server with RDSH role installed VMware virtual Audio and VMware Virtual Microphone drivers are not installed, as opposed as to a client OS.
On windows 10, in device manager these drivers are added when the Horizon Agent is installed. On a Windows 10 guest RTAV works as designed. The Philips Speech devices with Dragon Naturally Speaking setup is fully functional.
What I notice, is that on Windows 2016 RDS, these drivers are NOT installed with the Horizon Agent. On this 2016 RDS guest, RTAV is not working. (I also tested this on 2012; same behaviour)
I spent already hours with support, but they seem unable to solve it.
Hopefully someone on the forum, can help me with this.
