Microsoft has resolved a known issue that caused Always On VPN connection issues after installing the September 2026 Windows 11 security updates.
The Always On VPN remote access solution replaced the legacy DirectAccess technology and works with domain-joined, non-domain-joined, and Microsoft Entra ID–joined Windows 10, Windows 11, and Windows Server devices.
Always On VPN runs in the background and automatically establishes a secure tunnel back to the corporate network whenever a device connects to the internet.
As Microsoft first acknowledged in a service alert sent to IT administrators in late September, the bug triggered Always On VPN failures if the initial connection fails (e.g., when using automatic protocol selection with IKEv2 and SSTP) on up-to-date systems running Windows 11 24H2 and later.
On Tuesday, the company released the KB5127648 and KB5127646 cumulative updates that address this known issue on all affected systems.
"When automatic protocol selection or protocol fallback was configured, affected VPN connections could remain stuck in a Connecting state or fail to connect after an initial connection attempt failed," it said. "In some cases, subsequent connection attempts could display the error, 'The specified port is already in use.'"
Microsoft has also shared a temporary fix for customers who can't immediately install the October 2026 Patch Tuesday update, which requires them to choose one of two VPN tunneling protocols to work around the issue.
"IT administrators can mitigate this issue by changing the Always On VPN profile from automatic protocol selection to a single protocol, either SSTP only or IKEv2 only, depending on their environment and configuration," Microsoft said. "Organizations should select the protocol based on their environment, security, and deployment requirements."
Last month, it released emergency updates to fix Remote Desktop Services failures, Hyper-V issues, and USB audio problems affecting home and enterprise Windows users, which were also triggered by the September 2026 updates.
This week, it also confirmed that non-admin users may have issues connecting to devices via Remote Desktop after installing recent Windows updates if the "Administrator protection" security feature is enabled.
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