VPN Slow Network Speeds

Question

VPN Slow Network Speeds

zedyep 10

We have been experiencing issues with users having internet connection speeds dropping to <1Mbps download speeds when connecting to the company VPN.

It started when the Windows security update (KB5026372) was installed. We were initially able to fix the issue by uninstalling that update, but now we are experiencing the same issue when the update doesn't appear to be installed.

We tried connecting to the VPN with a machine that was freshly imaged and had nothing but the VPN configured on it. The issue was still happening.

This has been very disruptive to us conducting business and we have had trouble narrowing down what is causing it.

All devices are on Windows 11.

CLERGET Alexis 10 Reputation points

2023-10-27T16:03:58.1566667+00:00

Had the issue after windows updates on clients with our VPN L2TP/IPSEC and fixed it this way :

Slow access to local network :

services.msc -> Routing and remote access -> change "start type" to Automatic (Delayed start) and click "Start"

Establish a LT2P connection. FIXED

Slow access to the internet :

internet options -> Connexions -> VPN -> settings -> propriétés -> network management -> Internet Version 4 Protocol -> use this adress for DNS Server -> favorite 1.1.1.1 / auxiliary : 8.8.8.8
zedyep 10 Reputation points

2023-10-27T16:07:07.4933333+00:00

This is exactly what we ended up doing. I totally forgot to come back and add the solution to the post.

1 answer

Your answer

CLERGET Alexis 10 Reputation points

2023-10-27T16:03:58.1566667+00:00

Had the issue after windows updates on clients with our VPN L2TP/IPSEC and fixed it this way :

Slow access to local network :

services.msc -> Routing and remote access -> change "start type" to Automatic (Delayed start) and click "Start"

Establish a LT2P connection. FIXED

Slow access to the internet :

internet options -> Connexions -> VPN -> settings -> propriétés -> network management -> Internet Version 4 Protocol -> use this adress for DNS Server -> favorite 1.1.1.1 / auxiliary : 8.8.8.8
zedyep 10 Reputation points

2023-10-27T16:07:07.4933333+00:00

This is exactly what we ended up doing. I totally forgot to come back and add the solution to the post.

Answer 1

Wesley Li-MSFT 4,576 Microsoft External Staff

Hello

There have been reports of the Windows security update KB5026372 causing issues with VPN connections, particularly with L2TP/IPsec VPNs. Some users have experienced a drastic decrease in download and upload speeds after installing the update. Uninstalling the update has been reported to resolve the issue for some users, but it appears that you are still experiencing the issue even after uninstalling the update. It is possible that there may be other factors contributing to the issue. You may want to try troubleshooting your VPN connection or contacting your VPN provider for assistance.

https://answers.microsoft.com/en-us/windows/forum/all/is-kb5026372-causing-an-issue-with-vpn-connections/e597f6f4-b961-4880-8c74-a392f3926457

If the response is helpful, please click "Accept Answer" and upvote it.

zedyep 10 Reputation points

2023-07-14T14:32:37.7033333+00:00

Thank you for your reply.

We have been troubleshooting and have not found a clear cause. The issue is intermittent. For example, yesterday afternoon I connected to the VPN from my home network and my speeds were consistent with not being on the VPN, then this morning I connected to the VPN on my cell phone hotspot at the office and speeds dropped to <1Mbps down. Speed on the hotspot without VPN was 200Mbps down The only changes were physical location and network I was connected to.

We have also spoken to our VPN provider. They told us it wasn't an issue on that end and to just uninstall the update.
zedyep 10 Reputation points

2023-07-17T14:41:58.76+00:00

Still experiencing the issues intermittently.

Share via

VPN Slow Network Speeds

1 answer

Your answer