September Windows Updates Break Always On VPN Connections

Always On VPN Connection Failures

Microsoft has informed IT administrators that installing the September 2026 Windows 11 security updates can lead to Always On VPN connection problems. Always On VPN is a remote access solution for Windows 10, Windows 11, and Windows Server, designed to provide automatic, secure connections to corporate networks.

Technical Details of the Issue

The issue arises when the VPN is set to automatically try different connection methods if the initial attempt fails, specifically when using automatic protocol selection with IKEv2 and SSTP. Affected VPN connections may get stuck in a 'Connecting' state or repeatedly attempt to connect without success. Users might also encounter an error message stating, 'The specified port is already in use.'

Temporary Mitigation Provided

While Microsoft is developing a permanent fix, a temporary workaround is available. IT administrators can mitigate the problem by modifying the Always On VPN profile to use a single protocol, either SSTP only or IKEv2 only, instead of automatic protocol selection. The choice of protocol should align with the organization's environment and security requirements.

Broader Update-Related Problems

This VPN issue is one of several problems linked to the September cumulative updates. Earlier, Microsoft released emergency updates to address Hyper-V issues, Remote Desktop Services failures, and USB audio problems also caused by the September 2026 updates. The company is also working on fixes for other issues, including one preventing some Windows 11 users from logging in with valid domain credentials.