Microsoft is investigating speed issues affecting L2TP/IPsec VPN after installing the latest Windows 11.
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According to reports from Windows users and administrators, the connection bandwidth limitations were first caused by an insecure, optional update , codenamed KB5025305.
The company rolled out the same fixes and improvements included in the preview update KB5025305 in the mandatory cumulative update KB5026372 that was released during this month's patch. This means that connection issues will be resolved for more Windows users.
Based on the reports seen by BleepinComputer since the time the updates became available, both updates cause speed issues on L2TP/IPsec VPN after their installation.
"No issues connecting to VPN, once logged in, speeds are extremely slow and RDP basically dies. A quick search online confirms that KB5025305 is causing speed issues on L2TP/IPsec VPN," a Windows admin shared on Reddit.
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Additional reports from users reveal that this issue only affects Wi-Fi connections and not wired connections, as it appears.
«Microsoft knows the issue and is looking into it», said a spokesperson on Monday regarding speed issues.
Although there is no solution for the issue on affected Windows 11 systems until a fix is released by Microsoft, administrators recommend uninstalling the updates that are causing the issue.
However, it should be noted that the company bundles all security fixes into one updated version. So, uninstalling the KB5026372 update will also remove all recent fixes for specific security issues. However, it may fix the VPN speed issues.
Some users are reporting that KB5025305, an optional update, is causing SSDs and affecting write speeds, while others are experiencing performance issues in games.
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Microsoft released out-of-band (OOB) emergency updates in January 2022 to fix connection issues with L2TP VPN using the Windows VPN client. These issues were caused by codebase updates released by Microsoft on the January 2022 Patch Tuesday.
