Microsoft’s first Patch Tuesday of 2022 appears to be cursed with issues. Users are reporting that KB5009543 for Windows 10 2004, 20H1, and 21H1 is causing issues connecting to VPN for a number of clients and servers over the L2TP VPN protocol.
Users are reporting running into the “Can’t connect to VPN. The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer,” error, and is mainly affecting the built-in Windows VPN client when connecting to Ubiquiti Client-to-Site VPN, SonicWall, Cisco Meraki, and WatchGuard Firewalls.
The main workaround is to uninstall KB5009543 by going to Control Panel> Programs -> View installed updates.
Are any of our readers running into this issue? Let us know below.