Microsoft: September Windows updates break Always On VPN connections

Key Points:

• Microsoft has alerted IT administrators that the September 2026 Windows 11 security updates may cause Always On VPN connection issues, with VPN connections getting stuck in a "Connecting" state or showing port usage errors.
• Always On VPN, used across Windows 10, 11, and Windows Server, automatically establishes secure tunnels to corporate networks and supports modern protocols like IKEv2 and SSTP, as well as multi-factor authentication.
• The issue arises when VPN is set to automatically switch connection methods if the initial attempt fails, causing repeated connection attempts without success.
• As a temporary workaround, Microsoft advises IT administrators to configure Always On VPN to use a single tunneling protocol (either SSTP or IKEv2) instead of automatic protocol selection.
• The September 2026 cumulative updates have also caused other problems, prompting Microsoft to release emergency fixes for Hyper-V, Remote Desktop Services, and USB audio issues last week.