After installing the May 2023 Microsoft updates, VPNs based on L2TP/IPsec protocols become inexplicably slow.

Microsoft has confirmed that it is working to verify multiple reports that are coming from users of Windows 11 who have installed the May 2023 security updates. This time the complaints have a lowest common denominator: the vpn connections based on the L2TP/IPsec protocols have become inexorably slow after applying this month’s patches. In another article we have seen the main differences between VPN protocols and how to create a VPN server in Windows Server without installing third-party software.

After installing the security updates of May, the connection with the VPN servers is without problems but once connected with the remote host, the access to any resource of the network becomes almost impossible. Quite often companies protect access via Remote Desktop by allowing remote administration connections only prior connection with the VPN server. The fact is that after installing the cumulative update for Windows 11 KB5025305all services “behind” the VPN become slow and practically unusable.

Furthermore, the problem would seem limited to users who use Windows 11 clients on a WiFi connection while it would not concern devices connected to the network via an Ethernet cable.

Microsoft admitted that they are aware of the issue but cannot currently recommend corrective actions to mitigate the issue. In addition to keeping an eye on updates on the Known issues page, users affected by the problem obviously can uninstall package KB5025305 of May 2023 by looking for it on the screen that appears by pressing the key combination Windows+Rtyping appwiz.cpl then choosing View installed updates.

Because removing the cumulative update removes all fixes security vulnerabilities on which Microsoft technicians intervened this month, it is important to evaluate – perhaps by referring to the article mentioned at the beginning and to the May 2023 bulletin – whether it was appropriate to download and install individual patches to correct particularly serious problems.

After installing the May 2023 Microsoft patches, other users are reporting cryptic errors installing updates while others point out SSD performance significantly reduced compared to the previous situation.


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