https://arstechnica.com/gadgets/2022/01/microsoft-fixes-patch-tuesday-bug-that-broke-vpn-in-windows-10-and-11/

Microsoft's monthly Patch Tuesday updates for Windows are generally meant to fix problems, but that isn't how it always goes. January's updates, released last week, caused a handful of problems for businesses in particular. The most serious, especially for people still dealing with pandemic-driven remote-work setups, was a bug that broke certain kinds of VPN connections. Microsoft has provided fixes for this and other issues as of today, a few days after acknowledging the problem on its Known Issues page.

According to Microsoft's documentation and reporting from Bleeping Computer, the VPN connection issues affected "IPSEC connections which contain a Vendor ID," as well as L2TP and IPSEC IKE VPN connections in Windows 10, Windows 11, and Windows Server versions 2022, 20H2, 2019, and 2016. Windows' built-in VPN client seems to be the most commonly affected, but third-party VPN clients using these kinds of connections could also run into the error.