HowTo: Use a WRT54GL as a Repeater with a FritzBox 7270 Including WPA Encryption

This HowTo explains how to connect a WRT54GL V1.1 to a FritzBox 7270 as a repeater. In this setup, the WRT54 receives the FritzBox Wi-Fi signal and rebroadcasts it using the same SSID. Computers connected to the WRT54 by LAN cable are on the same network as the Wi-Fi devices. The connection uses WPA encryption. In principle, this configuration therefore provides much the same functionality as a dedicated Wi-Fi repeater.

Hardware and Firmware Used

FritzBox 7270 firmware version 74.04.88

WRT54GL V1.1 firmware: DD-WRT v24-sp2 (build 14896)

Configuring the FritzBox

Basically, I use the FritzBox standard configuration:

IP address: 192.168.178.1
Subnet mask: 255.255.255.0
DHCP server: enabled
The DHCP server assigns IP addresses from 192.168.178.20 to 192.168.178.200

These values can of course vary. The following WRT54 configuration, however, is based on this setup.
Naturally, Wi-Fi must be enabled on the FritzBox. You should set the wireless channel manually. This can be done in the FritzBox interface under “Wi-Fi” → “Radio Channel”. Ideally, use channel 1, 6 or 11.

The Wi-Fi network name should be set to visible, at least while setting everything up. Once the repeater has been configured, you can hide it again. Under “Security”, enter the following settings:

Security: WPA encryption
WPA mode: WPA + WPA2
Wi-Fi network key: a secure key

Configuring the WRT54

If you have not already done so, the special DD-WRT firmware must be installed on the router. The firmware and further information are available at www.dd-wrt.com. In any case, start by performing a router reset. Then connect via LAN cable with DHCP enabled and open the router web interface. It can normally be reached at the router’s default IP address.

After setting a username and password in the router web interface, it is best to go first to the “Status” page and then to the “Wireless” section. Under the wireless nodes section, start the site survey.

A new window now opens showing all available Wi-Fi networks. The FritzBox network should appear here. If it does not, you are either outside the FritzBox wireless range or something is wrong with the FritzBox configuration.

In the list of available networks, click “Join” on the right. Then switch to the main “Wireless” menu and edit the physical wl0 interface under “Basic Settings” as follows:

Wireless mode: Repeater Bridge
Wireless network mode: G-Only
Wireless network name (SSID): the name of the network joined above should already be shown here; otherwise enter the FritzBox Wi-Fi network name.
Sensitivity range (ACK Timing): 0
Network configuration: Bridged

Then save, but do not apply the settings yet. Still under “Basic Settings”, edit the virtual wl0.1 interface as follows:

Wireless network name (SSID): the FritzBox Wi-Fi network name, i.e. the same as above. While setting up the repeater, you can temporarily use a different name to verify that the WRT54 is working.
Wireless SSID broadcast: initially leave this enabled and disable it only after the configuration works and you want to hide the network.
AP Isolation: disabled
Network configuration: Bridged

Now “Apply” these changes. Then switch to “Wireless Security” and configure the physical wl0 interface as follows:

Security mode: WPA2 Personal
WPA algorithm: TKIP+AES
WPA Shared Key: use the same key as the FritzBox “Wi-Fi network key”.
Key Renewal Interval (seconds): 3600

Before the next step, be sure to save. Then enter the same settings again for the virtual wl0.1 interface as for the physical interface. Apply the settings, switch to the main “Security” menu, clear all checkboxes under additional filters and WAN blocking, and then disable the firewall completely. Apply these changes as well.

If you now return to “Status”, the FritzBox should already be visible by its MAC address under the wireless nodes section. Finally, go to the main “Setup” menu once more. Under “Networking”, add an additional DHCP server on eth0 under “DHCPD” and save the setting.

Now return once more to “Basic Setup” and configure the router IPs under “Network Setup”.

Local IP address: a free IP address on the FritzBox network that is not assigned by the DHCP server. I used 192.168.178.2.
Subnet mask: the same as on the FritzBox; in my case 255.255.255.0
Gateway: enter the FritzBox IP address, in this case 192.168.178.1
Local DNS: 0.0.0.0

After applying these settings, the configuration is complete. You will probably need to renew the IP address on the PC used to configure the WRT54, or adjust any manually assigned address. The WRT54 should now receive and rebroadcast the FritzBox Wi-Fi network. If the same SSID has been used everywhere as described here, a laptop should automatically switch between the FritzBox and WRT54 networks.

What apparently does not work is switching between the FritzBox and repeater networks while, for example, making a Skype call or streaming a radio station on an iPhone. Unfortunately, the iPhone app I used usually even crashes during the switch. The repeater web interface can be reached via its IP address, in this case 192.168.178.2.