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Knowledge document #3229

Setting up the FRITZ!Box as a cascaded router

You can set up your FRITZ!Box for use as a cascaded router and connect it to your other router using a network cable. The FRITZ!Box then uses the existing internet connection of your other router, but it still provides its own network that is separate from the other router. In this case

  • the firewall of the FRITZ!Box is enabled.
  • computers, smartphones, and other devices connected to the FRITZ!Box no longer obtain their IP settings from the other router. Instead, they obtain them from the FRITZ!Box.

Requirements / Restrictions

  • It is not possible to access devices connected to the FRITZ!Box from the other router's network.
  • Depending on the other router, functions that require a public IP address (for example port sharing and receiving incoming VPN connections) can either not be used, or can only be used to a limited extent.
  • The FRITZ!Box and the other router must use different IP networks.

    Note:In the factory settings, the FRITZ!Box uses the IP network (subnet mask The IP network can be adjusted as described in the guide Changing the FRITZ!Box's IP address.

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

1 Configuring the operating mode

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "Account Information" in the "Internet" menu.
  3. Select "other internet service provider" from the drop-down list "Internet service provider". If this entry is not available, select "more internet service providers" first.
  4. Enable the option "Connection to an external modem or router" in the "Connect via" area.
  5. Enable the option "Establish own connection to the internet" in the section "Operating Mode".
  6. Enable the option "No" in the section "Account Information".
  7. Enter the speeds of your internet connection in the "Downstream" and "Upstream" fields.
  8. Click "Change connection settings".
  9. If the other router provides a DHCP server, enable the option "Obtain the IP address automatically (DHCP)".
    • If the other router does not provide a DHCP server:
      1. Enable the option "Configure the IP address manually".
      2. In the "IP address" field, enter an unused IP address from the router's IP network.

        The router has the IP address (subnet mask This means that it is in the IP network If the IP address is not being used by any other device, you can use it.

      3. Enter the subnet mask of the router in the "Subnet mask" field.
      4. Enter the IP address of the router in the "Default gateway" and "Primary DNS server" fields.
  10. Click "Apply" to save the settings.

2 Connecting the FRITZ!Box with the network

  1. Use a network cable to connect the "WAN" port on the FRITZ!Box either directly to a LAN port on the router, or via a hub or switch.

3 Opening the user interface

On devices connected with the FRITZ!Box via a LAN port or the Wi-Fi network, you can enter to open the user interface.

If you also want to open the FRITZ!Box user interface with devices that are connected to the other router, you must enable internet access via HTTPS in the FRITZ!Box and set up a FRITZ!Box user who is allowed to access the FRITZ!Box from the internet:

  1. Click "System" in the FRITZ!Box user interface.
  2. Click "FRITZ!Box Users" in the "System" menu.
  3. Click the "Add User" button.
  4. Enter a username and a password for the user.
  5. Enable the option "Access from the internet allowed".
  6. Enable the option "FRITZ!Box settings" under "Rights".
  7. Click "Apply" to save the settings.
  8. Click "Permit Access" in the "Internet" menu.
  9. Click on the "FRITZ!Box Services" tab.
  10. Enable the option "Internet access to the FRITZ!Box via HTTPS enabled".
  11. Click "Apply" to save the settings.

You can now also open the FRITZ!Box user interface with devices connected to the other router using the address in the field "Web address of your FRITZ!Box" (for example

4 Setting up telephony

If you want to connect telephones to the FRITZ!Box and then use them to make telephone calls over the other router's internet connection: