Carboni: Jittery mouse when controlling Win10 version 1903 via RDP? There’s a solution.

From Noel Carboni:

Have you seen a jittery mouse or black screen when controlling a Windows 10 v1903 or newer system via RDP?  I’ve discovered a workaround.

When I upgraded my office computer to Windows 10 v1903 it created a new problem.  When I used my company’s VPN and RDP to control it remotely, the mouse would stutter or jitter.  RDPing into my office system is something I had been doing quite effectively and seamlessly when it was running Win 10 v1809, without any hint of such a problem.  The only thing that changed coincident with the introduction of the problem was the office system’s OS version.

Based on observation, with Win 10 v1903, whenever a new graphic is loaded into the mouse cursor (e.g., the arrow changes to a finger or spinner or whatever) the cursor pointer is moved back to the position it was in where the change was requested by the controlled system.  This may not seem like a big deal, but trust me, while it does not leave the system completely unusable, when you move the mouse anything but excruciatingly slowly it makes it just plain irritating to use.

A bunch of web searches later, culminating in a visit to the VMware workstation forum, I learned that Microsoft has enabled (and made default) the use of a second driver model on the system being controlled:  The WDDM model.  Up to now RDP has run off the XDDM display driver model, which is apparently better optimized for an interface that takes a noticeable amount of time to update a mouse cursor given mouse position input.  Remote connections take milliseconds, if not tens or hundreds of milliseconds.  Therein lies the problem.

For some folks trying to make use of this combination of software and OS versions, the problem can be even worse:  They just get a black screen.  Do a search for “Windows 10 WDDM RDP” on Google and you’ll see that a fair number of folks are having RDP problems.

The good news:  It turns out Microsoft thought ahead (as they often do) and provided a new policy for configuring the controlled system to use the older, tried and proven XDDM model.  If you have Windows 10 Pro, run gpedit.msc and navigate to the following:

Local Computer Policy
Computer Configuration
Administrative Templates
Windows Components
Remote Desktop Services
Remote Desktop Session Host
Remote Session Environment

Set the Use WDDM graphics display driver for Remote Desktop Connections policy to Disabled

This will clear up jittery mouse and black screen problems and make a remote Windows v1903 (or Server 2016) or newer system a pleasure to use via RDP again.

UPDATE: Interesting. There’s a post on the Microsoft Answers forum from KevinMarchant that complains about the “high CPU after disconnecting” problem on Win10 1903. That post is now marked “*** PROBLEM RESOLVED BY KB4522355 RELEASED OCTOBER 24TH 2019. ***”

Any chance that the latest optional, non-security update actually fixes the mouse jitters, too?

The KB article says:

Addresses an issue with high CPU usage in Desktop Window Manager (dwm.exe) when you disconnect from a Remote Desktop Protocol (RDP) session.