FRITZ!Box 4020 Service - Knowledge Base

FRITZ!Box 4020 Service

Setting up the FRITZ!Box as a cascaded router

When the FRITZ!Box is used as a cascaded router, it 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: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. Open the FRITZ!Box user interface.
  2. Enter the FRITZ!Box password on the bottom of the device and click "Log In".
  3. Click "Internet" and then "Account Information".
  4. Select "Cable modem or internet router" from the drop-down list "Internet connection via".
  5. Enter the speeds of your internet connection in the "Downstream" and "Upstream" fields.
  6. Click "Change Connection Settings".
  7. 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.
  8. Click "Apply" to save the settings.

2 Connecting the FRITZ!Box with the network

  1. Use a network cable (for example the white network cable included with delivery) to connect the "WAN" port on the FRITZ!Box either directly to a LAN port on the router, or by means of a hub or switch.

3 Opening the user interface

Enter as usual to call up the user interface with devices connected to a LAN port or to the FRITZ!Box's Wi-Fi network.

Proceed as follows to open the user interface with devices connected to the other router instead of the FRITZ!Box:

  1. If the FRITZ!Box obtains its IP address via DHCP, enter the IP address that the router assigned to the FRITZ!Box, for example, in the web browser.
    • If you assigned an IP address to the FRITZ!Box, enter the IP address that you entered in the "IP address" field in the user interface, for example, in the web browser.
  2. In the corresponding fields, enter the user name and password of a FRITZ!Box user who is authorized to access the FRITZ!Box from the internet and click "Log in".

    Note:You can edit the access rights of FRITZ!Box users under "System > FRITZ!Box Users" in the user interface.