Microsoft has confirmed that April’s security updates and non-security preview updates may cause VPN connection issues on Windows 10 and 11, as well as various versions of Windows Server. On server systems that act as domain controllers, security updates may also result in a large increase in NTLM authentication traffic.
The latter concerns according to Microsoft “likely organizations that have a very low percentage of primary domain controllers in their environment and have high NTLM traffic”. For the occurrence of the VPN connection problems says the company however, no further conditions.
Affected Windows versions and updates
The following client systems and updates are only affected by the VPN issues mentioned:
The list of affected Windows server versions looks identical for the VPN and NTLM issues:
Fixes are in the works
Microsoft currently does not offer an official workaround for either problem. The group simply assures that it is already working on a solution and will provide it in a future update. Affected private users are referred to the request help app preinstalled on Windows systems for support, while companies are referred to business support.
Uninstalling the problematic April updates should certainly help. However, administrators who choose this step should be aware that this will remove all patches distributed with the respective update. Affected systems become vulnerable again to known security gaps that Microsoft closed in April.