Client VPN stopped working Windows 7 and 10

VPN
1

I have 2 workstations whose client vpn stopped connecting.

The error generated is “the l2tp connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer.”
Event log reads “The error code returned on failure is 789”

Other workstations and phones connect w/o issues, it’s just these two units that all of a sudden stopped connecting.
Meraki support suggested reinstall of Windows…?!
Surely there must be an easier way, anyone has any experience repairing this?

2

I had a similar problem on some of my devices after a Windows update. For whatever reason, my VPN profile had been changed to MS-ChapV2 (Meraki only support PAP). Double check your adapter settings for the VPN profile under the security tab and make sure ONLY the PAP option is checked.

3

My bet would be on a 3rd party VPN client being installed on the machines

IKE and AuthIP IPsec Keying Modules disabled (Windows only)
Solution: This occurs most often when 3rd party VPN software has been installed and disables the IKEEXT service. This can be re-enabled by navigating in Windows to Control Panel > Administrative Tools > Services. Find the service named “IKE and AuthIP IPsec Keying Modules” and open it. Change the Startup type to “Automatic”. If this automatically reverts to “Disabled” or fails to start, it may be necessary to remove the 3rd party VPN software:

4

Do you have a firewall or NAT device upstream of your clients? Make sure their configurations allows for VPN traffic to flow appropriately.

Also, if your device is behind a NAT you may have to configure registry entries. Check out error 809 (Troubleshooting Client VPN - Cisco Meraki Documentation).

5

I’m pretty sure some of my users get this when the network they are on is blocking VPN connections. AT&T hotspots seem to cause this error sometimes too

6

I’m seeing this with Windows 10 clients randomly as well. I’ve tried new connections, shared secrets, credentials, all that. Frustrating for sure.

7

This. It happens pretty frequently on Windows 10 machines.

8

thanks for your reply, we’ve already been through the documentation

9

thank you for the suggestion, tested and this service runs as expected
edit-> wanted to add that yes, i do have other 3rd party vpn software; however, meraki was working just fine along with them until it broke for whatever unknown reason.

10

thank you, this was already tried and didn’t provide results

11

Many cellular hotspots break NAT-t for IPSec VPNs because they perform special IPv6 NAT to the connection mid-transmission, or they block ports. People email in about this all the time.

12

You seem to think it’s the Meraki suddenly causing an issue. It could be, but it could equally be your 3rd party VPN updated itself and borked your Windows VPN client. Or, you know, Windows.

13

definitely not the meraki as many other windows systems / phones are working still fine. the issue is isolated to a single windows 10 and windows 7 machine.