The October cumulative update KB5127648 for Windows 11 versions 24H2, 25H2, and 26H2 contains a bug affecting network connectivity. Users report that the update disrupts Wi-Fi connections that utilize WPA 802.1X PEAP authentication, which is commonly deployed in corporate and academic environments.
Affected users experience repeated credential errors or are unable to connect to their networks entirely. The issue has impacted employees and students globally who rely on these enterprise-grade security protocols for their daily operations and studies.
To address the connectivity failure, administrators can modify the registry. By creating or adjusting the BlockNtlmv1SSO DWORD value within the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0 path and setting it to 0, the authentication issue is resolved.
IT administrators managing large fleets of devices have confirmed that deploying this registry change via Group Policy effectively restores network access across multiple machines.
