As a result, the L2TP layer doesn't see a response to its connection request. If the IPSec layer can't establish an encrypted session with the VPN server, it will fail silently. When it starts, you receive a prompt for your name and password (unless the connection has been set up to connect automatically in Windows Millennium Edition.) If the VPN server accepts your name and password, the session setup completes.Ī common configuration failure in an L2TP/IPSec connection is a misconfigured or missing certificate, or a misconfigured or missing preshared key. When an IPSec security association (SA) has been established, the L2TP session starts. Depending on many factors including link speed, the IPSec negotiations may take from a few seconds to around two minutes. This packet causes the IPSec layer on your computer to negotiate with the VPN server to set up an IPSec protected session (a security association). When you start the connection, an initial L2TP packet is sent to the server, requesting a connection. When you troubleshoot L2TP/IPSec connections, it's useful to understand how an L2TP/IPSec connection proceeds.

If you try to make a VPN connection before you have an Internet connection, you may experience a long delay, typically 60 seconds, and then you may receive an error message that says there was no response or something is wrong with the modem or other communication device.

You must have an Internet connection before you can make an L2TP/IPSec VPN connection.

This article describes how to troubleshoot L2TP/IPSec virtual private network (VPN) connection issues.Īpplies to: Windows 10 - all editions Original KB number: 325034 Summary

Fortigate debug ipsec