Microsoft has acknowledged a Windows 11 bug that can prevent Windows Subsystem for Linux (WSL) from accessing corporate resources through some third-party VPNs when mirrored networking is enabled. The company says the issue affects systems running the October 28, 2025, non-security preview update or subsequent updates.
The affected releases include that preview update, KB5067036, and KB5072033, the cumulative security update released on December 9, 2025 for Windows 11 versions 24H2 and 25H2.
Microsoft says affected WSL environments may display a “No route to host” error when connecting to destinations over a VPN, even though the Windows host can still reach those same destinations. Services that depend on the VPN connection may also fail.
The company attributes the problem to the VPN application’s virtual network interface failing to respond to Address Resolution Protocol (ARP) requests. Microsoft says reports indicate that Cisco Secure Client, formerly Cisco AnyConnect, and OpenVPN are affected.
Microsoft says home users running Windows Home or Pro editions are unlikely to encounter the issue, which primarily affects connectivity to enterprise resources over VPN, including DirectAccess.
At the time of the December 15, 2025, report, Microsoft said the issue was under investigation and that it would share additional information as it became available.
Mirrored networking in WSL
Microsoft introduced mirrored networking in September 2023 as an opt-in experimental feature designed to mirror Windows network interfaces into Linux. The company listed improved VPN compatibility, direct access to WSL from a local area network and connections from Linux to Windows servers through the localhost address among its benefits.
Mirrored mode is an alternative to WSL’s default networking architecture, which uses Network Address Translation (NAT).
WSL was first announced in 2016 to bring Linux command-line tools to Windows. Microsoft announced WSL 2 in 2019, introducing an architecture that runs a Linux kernel in a lightweight virtual machine. At Build 2025, Microsoft made WSL’s source code available on GitHub, while some components integrated into Windows remained closed.
