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This document describes the information that needs to be collected in order for our Support to determine the cause of this behavior.

This article describes how to troubleshoot problems with a VPN connection between two routers. How to troubleshoot a problematic VPN connection when using the Advanced VPN Client is described in this Knowledge Base article.



Generating traces on a LANCOM router:

1) Using the LANtracer, connect to the affected router and load the attached trace configuration into the trace module.

If this is a VPN connection between two LANCOM routers, the traces must be created on both routers at the same time. 

The traces must be created locally and not via the VPN connection, as otherwise important information will be lost if the connection is broken!


The procedure for creating traces using a ready-made trace configuration is described in this Knowledge-Base article.

2) If several VPN connections terminate on the router, the VPN-IKE trace must be filtered for the public IP address of the other VPN participant by means of the Filter field.

If the other VPN subscriber has a dynamic IP address and can be reached at a DynDNS address, enter the currently assigned IP address.

Only the VPN-IKE trace should be filtered.

3) Start the trace by clicking the button with the green arrow and record the occurrence of the error.

The trace must include the attempt to connect and/or the termination.

4) Stop the trace by clicking on the button with the stop sign and save it.

Collecting information from routers from other manufacturers:

If one of the two routers is a device from another manufacturer, we need the following information from this device:

  • VPN configuration in text form or screenshots
  • VPN debug information, which documents the behavior of the device. These must be created at the same time as the trace of the LANCOM router.