Windows updates address Always On VPN failures, but users report new issues

Microsoft released the cumulative updates KB 5127646 and KB5127648 to address connection failures affecting Windows’ Always On VPN feature. The problems followed a Windows update in September 2026, according to a report by Bleeping Computer.

Always On VPN is built into Windows 10, Windows 11 and Windows Server. It can activate a VPN automatically when a computer detects an internet connection. Microsoft told IT administrators in a September 2026 alert that the feature could fail if a computer could not connect to the internet initially. Repeated attempts could show the error “The specified port is already in use.” The issue affected devices running Windows 11 24H2 or newer.

Microsoft said administrators unable to install the updates could temporarily set the VPN profile to use only SSTP or only IKEv2, depending on their environment and configuration.

Some users say the patch also improved other VPN connections, though it is unclear whether that was intended. A Reddit user reported better speed and stability with Surfshark after installing the Windows 11 update dated October 13, 2026, following about two months of instability, particularly when waking the computer from Sleep mode.

Other users reported trouble connecting to company Wi-Fi after the update. Reports and forum posts pointed to possible effects on 802.1x PEAP connections and NTLMv1 authentication, but Microsoft had not confirmed those issues in the supplied source.