Windows 11: Always On VPN failures from September updates fixed in KB5127936
Summary
Always On VPN profiles with automatic protocol selection or fallback (IKEv2 and SSTP) failed after the September 2026 Windows 11 updates. According to secondary sources and research notes, the optional preview update KB5127936 (28 Oct 2026) fixes this. We could not read the vendor page ourselves, so the details are not yet confirmed by a vendor source here.
Symptoms
- After a failed first connection attempt, the VPN connection stays stuck in "Connecting" or fails.
- Later attempts can show "The specified port is already in use."
- Profiles set to a single protocol are not affected.
Affected
- Windows 11 25H2 and 26H2 (per reports; versions hit by the bug itself not verified)
- Always On VPN profiles with automatic protocol selection or protocol fallback (IKEv2 and SSTP)
- September 2026 security updates (one third-party article names KB5124008, not verified)
Workaround
- Change the Always On VPN profile from automatic protocol selection to a single protocol, either SSTP only or IKEv2 only, depending on your environment.
- After installing the fixed update, revert the profile to automatic selection.
Fix
Reportedly fixed in KB5127936 (optional preview update, 28 Oct 2026): build 26200.9818 for 25H2 and 26300.9818 for 26H2. A fix note in KB5127648 (13 Oct 2026) was retracted on 20 Oct 2026. Reports say the fix is also in the Patch Tuesday update expected 10 Nov 2026; this is not confirmed. The update is also available via the Microsoft Update Catalog and WSUS. KB5127936 only fixes this specific condition.
Recommendation
If affected, apply the single-protocol workaround now. Test KB5127936 on a pilot group, or wait for the November Patch Tuesday update, then revert the profile. Check other VPN problems separately, as they may have other causes.
Reports from the community and trade media
Reports from forums, Q&A sites, Reddit and trade media – linked only, without the names of the authors; the vendor’s statement is authoritative.
- Microsoft Fixes Windows 11 Always On VPN Failures From September Updates in KB5127936 News · gHacks, 31 Oct 2026
Sources
- gHacks: Microsoft fixes Windows 11 Always On VPN failures in KB5127936 News · www.ghacks.net
- Microsoft: KB5127936 release notes Vendor · support.microsoft.com
- BleepingComputer: Microsoft finally fixes VPN issues caused by September updates News · www.bleepingcomputer.com
- Microsoft Update Catalog: KB5127936 Vendor · www.catalog.update.microsoft.com
Compiled from community reports and web research and translated with AI (Claude) – not yet confirmed by the vendor. The vendor’s statements are authoritative. Updated 1 Nov 2026, 18:37.
Where the information comes from
We continuously read the vendors’ official sources, community reports and trade media and summarise them in our own words, with a link to the source:
- Microsoft: Windows release health (Windows 10/11, Server 2016 to 2025), Windows message center, known issues of Microsoft 365 Apps (Outlook, Excel, Word, PowerPoint), Edge, Intune, Autopilot, Windows 365 and Entra Connect, Microsoft KB articles with timelines, Exchange and Windows IT Pro blogs, optionally Microsoft 365 service health and message center
- other vendors: Veeam KB, Citrix (known issues), Ubuntu and Debian (regressions), Broadcom (VMware), Fortinet, Cisco, Mozilla, Let’s Encrypt
- community (title, short excerpt and link only, without the names of the authors): Microsoft Q&A, Microsoft Tech Community (discussions), Veeam R&D Forums, Eleven Forum
- targeted web research with AI (Claude), e.g. on the updates of the month – this also finds discussions on Reddit and in forums; such entries are labelled as community reports until the vendor confirms them
- early warning from trade media (title and link only): Born’s Tech and Windows World, BleepingComputer, AskWoody, Windows Latest, Windows Central, gHacks, The Windows Club, Deskmodder, Dr. Windows, WindowsArea, Frankys Web, heise online
Summary and translation with AI (Claude by Anthropic) – without any data of visitors.
Affected? We can help.
We check whether your systems are affected, apply workarounds properly and plan for dated changes in good time.