LANCOM Support Knowledgebase Dokument-Nr. 1901.2312.5821.RHOO - V1.50

Troubleshooting Guide: VPN connection with the Advanced VPN Client Version 4.10 or higher does not work with older LANCOM router models

This article describes what to do if a VPN connection with the Advanced VPN Client 4.10 or later does not work with an older LANCOM router model.

    When you set up an Advanced VPN Client profile for IKEv1, PFS group 14 is always set in the VPN profile by default.

    However, since this is supported only from the LCOS version 8.80, it comes to problems with older LANCOM routers to during the connection establishment.


1. You have a LANCOM router for which LCOS version 8.80 or higher is available:

1.1 In this case, perform a firmware update to the current LCOS version.

1.2 In the profile used under VPN -> IKE / IPSec -> Connection parameters, make sure that PFS Group 14 is selected.

2. You have a LANCOM router for which an LCOS version lower than 8.80 is available:

2.1 In this case, the PFS group in the Advanced VPN Client must be configured to the value DH2.

2.2 In the Advanced VPN Client under the item Profiles in the profile used, change to IPSec General Settings and select the value DH2 (modp1024) in the PFS group drop-down menu.

2.3 Save the profile. The connection to the LANCOM router must be established.
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