Microsoft has fixed a Windows 11 issue that caused Always On VPN connections to fail after users installed the September 2026 security updates, resolving a problem that had continued despite an earlier indication that it had already been addressed.
The company confirmed that the issue is fixed in the KB5127936 preview update released in October. The bug affected systems using automatic protocol selection or fallback between IKEv2 and SSTP for Always On VPN connections.
Always On VPN is Microsoft’s remote-access solution designed to establish secure connections between devices and corporate networks. It runs in the background and supports domain-joined, non-domain-joined and Microsoft Entra ID-joined devices running Windows 10, Windows 11 and Windows Server.
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VPN Connections Could Remain Stuck or Fail
Microsoft first acknowledged the problem in late September after the September 2026 Windows 11 security updates triggered connection failures on systems using automatic protocol selection with IKEv2 and SSTP.
According to Microsoft, affected VPN connections could remain stuck in a “Connecting” state or fail to establish a connection after an initial attempt was unsuccessful.
In some cases, users trying to connect again would receive an error stating that “The specified port is already in use.”
The issue affected Always On VPN configurations where automatic protocol selection or protocol fallback was enabled, rather than systems that were already configured to use only one tunnelling protocol.
Microsoft had previously marked the known issue as resolved in the October 2026 cumulative updates. However, the problem had not actually been fixed at that stage.
The company has now confirmed that users who install the KB5127936 preview update should receive the actual correction for the VPN failures.
Temporary Workaround Available for Administrators
Microsoft has also provided a workaround for organisations that do not want to install the preview update and prefer to wait for the next Patch Tuesday cumulative release.
IT administrators can change the Always On VPN profile from automatic protocol selection to a single tunnelling protocol.
Microsoft said administrators can configure affected systems to use either SSTP only or IKEv2 only, depending on the organisation’s existing environment and deployment requirements.
“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.
The company added that organisations should choose the appropriate protocol based on security requirements, infrastructure and deployment needs.
The workaround prevents the systems from switching between protocols, which was one of the conditions associated with the connection failures.
Preview Update Also Fixes Remote Desktop Issue
The October 2026 preview update also addresses a separate Windows 11 problem affecting Remote Desktop connections.
That issue prevented some non-administrator users from connecting to devices through Remote Desktop when the “Administrator protection” security feature was enabled.
The Remote Desktop problem was introduced after the September 2026 Windows 11 non-security preview update and also affected systems running later Windows updates.
The KB5127936 update therefore resolves two separate connectivity problems linked to recent Windows 11 updates, including the Always On VPN failures and the Remote Desktop access issue.
For organisations that rely on Always On VPN for secure remote access, the new fix provides a direct resolution to a problem that had persisted since September, while the single-protocol workaround remains available for administrators who prefer to wait for the next cumulative security update.
About the author — Suvedita Nath is a science student with a growing interest in cybercrime and digital safety. She writes on online activity, cyber threats, and technology-driven risks. Her work focuses on clarity, accuracy, and public awareness.
