I can confirm that "Prevent installation of devices not described by other policy setting", which I changed to "Not Configured" works !!!
But ! there was an issue with de device setup class settings in the GPO System/Device Installation/Device Installation Restrictions: "Allow non-administrators to install drivers for these device setup classes" or "Allow installation of devices using drivers that match these device setup classes"
I hade some default classes defined in there and the Mouse setup class {4d36e96f-e325-11ce-bfc1-08002be10318} was entered with a trailing space :-)
in the Windows\INF\setupapi.dev.log i noticed the following:
dvi: Class GUID of device changed to: {4d36e96f-e325-11ce-bfc1-08002be10318}.
ndv: {Core Device Install} 14:23:30.993
dvi: {Install Device - TERMINPUT_BUS\UMB\2&2C22BCC9&0&SESSION13MOUSE1} 14:23:31.009
dvi: Device Status: 0x01802400 [0x01 - 0xc0000361]
dvi: Parent Device: UMB\UMB\1&841921d&0&TERMINPUT_BUS
!!! pol: The device is explicitly restricted by the following policy settings:
!!! pol: [-] Restricted installation of devices not described by policy
!!! pol: {Device installation policy check [TERMINPUT_BUS\UMB\2&2C22BCC9&0&SESSION13MOUSE1] exit(0xe0000248)}
!!! dvi: Installation of device is blocked by policy!
dvi: Device Status: 0x01802400 [0x01]
dvi: {Install Device - exit(0xe0000248)} 14:23:31.040
dvi: {Core Device Install - exit(0xe0000248)} 14:23:31.056
Once i remove the trailing space in de GPO the logs shows: (after gpupdate)
: Previously blocked device is now allowed by policy [TERMINPUT_BUS\UMB\2&2C22BCC9&0&SESSION13MOUSE1]
pol: {Device Removal Initiated by Policy Change [TERMINPUT_BUS\UMB\2&2C22BCC9&0&SESSION13MOUSE1]}
So if you hav eany weird issues with RDP, not connecting, black screen or even disconnects after logon check the device log for device installation issues :-)