Security News > 2022 > January > New Windows KB5009543, KB5009566 updates break L2TP VPN connections
Windows 10 users and administrators report problems making L2TP VPN connections after installing the recent Windows 10 KB5009543 and Windows 11 KB5009566 cumulative updates.
These updates include KB5009566 for Windows 11 and KB5009543 for Windows 10 2004, 20H1, and 21H1. After installing yesterday's updates, Windows users find their L2TP VPN connections broken when attempting to connect using the Windows VPN client.
The bug is not affecting all VPN devices and seems only to be affecting users using the built-in Windows VPN client to make the connection.
A security researcher known as Ronny on Twitter told BleepingComputer that the bug affects their Ubiquiti Site-to-Site VPN connections for those using the Windows VPN client.
With many users still working remotely, admins have been forced to remove the KB5009566 and KB5009543 updates, which immediately fixes the L2TP VPN connections on reboot.
Windows users can remove the KB5009566 and KB5009543 updates using the following commands from an Elevated Command Prompt.