GoKawiilMicrosoft patches Always On VPN bug from September Windows updates
Microsoft released cumulative updates KB5127648 and KB5127646 fixing a bug that broke Always On VPN connections on Windows 11 24H2 and later systems after installing September 2026 security updates. The issue affected devices using automatic protocol selection between IKEv2 and SSTP, causing connections to hang or fail with a port-in-use error when an initial attempt didn't succeed.
GoKawiil's interpretation of the reporting above, not reported fact.
Always On VPN underpins remote access for many enterprises, so a flaw stranding devices in a perpetual connecting state could have disrupted remote work for organizations relying on automatic protocol fallback. Microsoft's interim workaround—forcing a single protocol—suggests the bug specifically stemmed from the fallback logic between SSTP and IKEv2 rather than the VPN feature itself.
- KB5127648 and KB5127646 fix Always On VPN failures caused by September 2026 updates on Windows 11 24H2+.
- Affected connections using automatic protocol selection could get stuck or show a 'port already in use' error.
- Until patched, IT admins can mitigate by setting VPN profiles to use only SSTP or only IKEv2.
Source: bleepingcomputer.com, 2026-10-14
Published there as: “Microsoft fixes VPN issues caused by September Windows updates”
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