Ok, thanks for replying. I did find a registry option which can be set via the "Gruppenrichtlinien" (can't find the english word for it) but that failed. Well, not completely, but Windows installed a security patch without asking.
So indeed Windows Updates need to be blocked completely.
I don't know if that relates, but after logging out of Remote Desktop, ST nealy came to a halt, blocked by a svchost.exe using ~25% CPU. Killing the task resumes ST. After I found the recent update I'm not sure if that was an immediate result or if the Remote Desktop disconnect does any harm to the Dante ASIO driver (it does kill all WASAPI, been through that before).
Using ST 9.35 and Win 10 Enterpise IoT LTSC as a platform for experiments with streaming output.
Don't use remote desktop because it often mess the audio drivers or address. Use teamwiever or anydesk instead.