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Knowledge document #342

IP communication over a VPN connection (LAN-LAN) is not possible

Although the VPN connection between two FRITZ! networks (LAN-LAN linkup) is established, computers and other devices in the network of the FRITZ!Repeater cannot access devices, shared files and printers, or other services in the remote FRITZ! network. Devices in the remote FRITZ! network do not respond to pings.

Simply proceed as described below. After each measure, check whether the problem is solved.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Repeater.

1 Deleting static IP routes

If static IP routes are set up in the FRITZ! network that point to the other FRITZ! network, reliable VPN communication is not possible.

Delete such static IP routes in the FRITZ!Repeater.

  1. Click "Home Network" in the user interface of the FRITZ!Repeater.
  2. Click "Network" in the "Home Network" menu.
  3. Click on the "Network Settings" tab.
  4. Click "Additional Settings" in the section "LAN Settings" to display all of the settings.
  5. Click the "IPv4 Routes" button.
  6. In the table, disable or delete all entries where the remote FRITZ! network is entered in the "Network" column.

    Example:
    The remote FRITZ! network uses the IP address 192.168.10.1 with the subnet mask 255.255.255.0. This means that no static IP route may be active for the IP network 192.168.10.0.

  7. Click "Apply" to save the settings.

2 Restarting the FRITZ!Repeater

You may be temporarily unable to correctly establish the VPN connection due to an error in the FRITZ!Repeater or its internet connection. Therefore, restart the FRITZ!Repeater so that it reinitializes the firewall and re-establishes the internet connection:

  1. Click "System" in the user interface of the FRITZ!Repeater.
  2. Click "Backup" in the "System" menu.
  3. Click on the "Restart" tab.
  4. Click the "Restart" button.

3 Configuring the device to automatically obtain IP settings

To ensure that the device always uses the correct IP settings, make sure that it automatically obtains its IP settings from the FRITZ!Repeater (this is the default setting for most devices):

  1. Configure the device to automatically obtain IP settings via DHCP.

4 Configuring the device's firewall

  1. If a firewall is installed on the device, configure it so that it does not block communication with the remote FRITZ! network (for example IP network 192.168.20.0). Refer to the manufacturer of the firewall for information on how to set it up, for example consult the manual.

5 Deleting a VPN connection and reconfiguring it

If IP communication over the VPN connection is still not possible, then the VPN connection is configured incorrectly, for example the IP address of the remote FRITZ!Box or remote FRITZ!Repeater (xxx.xxx.xxx.1) is entered instead of the IP network of the remote FRITZ! networks (xxx.xxx.xxx.0). Therefore, reconfigure the VPN connection:

  1. Delete the VPN connection in both FRITZ! networks (FRITZ!Box or FRITZ!Repeater).
  2. Use either IPSec or WireGuard to reconfigure the VPN connection between both FRITZ! networks.
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