Microsoft is investigating speed issues related to L2TP/IPsec VPN connections. Reports indicate that the problems began after the release of recent updates for Windows 11 and were initially associated with the optional update KB5025305, released in April. The fixes from KB5025305 were later included in the mandatory cumulative update KB5026372, released as part of the May “Update Tuesday”, after which more users experienced connection problems.
It appears that the error only affects Wi-Fi connections and does not affect wired connections. Reddit users report: “There are no issues with the VPN connection itself, but after that the speed becomes extremely slow, and RDP just times out. A quick web search confirms that KB5025305 is causing L2TP/IPsec speed issues.”
Microsoft has confirmed that they are aware of this problem and are looking into it. There is no patch yet, but removing the problematic service packs is reported to fix the problem. To do this, Microsoft suggests using the DISM /Remove-Package command line option with the LCU package name as an argument. The package name can be found with the command: DISM /online /get-packages.
Uninstalling cumulative update KB5026372 will also remove all fixes for newly patched vulnerabilities, although it will help resolve VPN speed issues.
