Wireless Repeater (Wireless Extender)

This network setup consists of a wireless access point and a wireless repeater. The access point is the device that connects to the main network using a wired connection and enables access to the internet. The repeater connects wirelessly to the access point as a station or client device. Once connected, it acts as a “bridge” or more accurately a point to point link, to provide access to that main network and to the internet for any wireless and wired client devices connected to the repeater. This setup is useful to extend the reach of your network, such as the Wi-Fi coverage on your location.

The method described in this article results in a backhaul link at layer 2 in the OSI model. All broadcast packets, such as DHCP requests, are sent in both directions over the link. The original source MAC address of the network devices on both sides are preserved over the bridge.

The client devices connected to the upstream access point and those connected to the repeater will be on the same subnet. In other words, they will be visible to each other and, therefore, enable the use of discovery and configuration protocols such as zeroconf. The upstream access point and the repeater remain accessible over the network.

Two wireless protocols can be used to achieve this, “WDS” and “802.11s-mesh”

This document will describe the use of WDS. For 802.11s mesh see: 80211s

The wireless distribution system technology (WDS mode) is required to create a network connection over a wireless link between the access point and the repeater device. The IEEE 802.11-1999 standard defines WDS as a mechanism for constructing 802.11 frames using a 4-address format, however, it does not define how to implement it or how stations interact to arrange for exchanging frames of this format ¹⁾. This may lead to problems when using WDS between network devices from different chipset and firmware vendors, so it is advisable to use OpenWrt both on the access point and on the repeater to use a shared implementation of this technology and increase your chances to make it work fine. Most wireless drivers in OpenWrt support the WDS mode.

• Tested with OpenWrt 12.09 using a TP-Link TL-WR1043ND as the upstream wireless access point and a Rosewill RNX-N300RT as the repeater.
• Tested with OpenWrt 15.05 using two TP-Link TL-WR1043ND.
• Tested with OpenWrt 15.05.1 using a Netgear WNDR3700v4 as the upstream access point and a Nexx WT3020 as the repeater.
• Tested with OpenWrt 19.07.2 to 19.07.6 using a Netgear R6220 as the upstream access point and a Wavlink WL-WN575A3 as the repeater. There were some glitches in 19.07.5 on the R6220, but seemingly not related to WDS.
• Tested with OpenWrt 21.02.1 with both a TP-Link EAP235-Wall V1 and a Netgear R6800 as upstream wireless access point, and D-Link DIR-878 A1 as the repeater (all MediaTek 802.11ac devices).
• Tested with OpenWrt 21.02.3 with Linksys WRT1900ACS v2 as upstream wireless access point, and Linksys EA8500 as the repeater.
• Tested with OpenWrt 22.03.2 with Banana PI BPI-R64 as upstream wireless access point, and Banana PI BPI-R2 as the repeater (AsiaRF AW7915-NP1 cards on both sides).

The network configuration process may be performed both via the command line (with uci and SSH) and via a GUI (with luci and a web browser). It is split in two sections:

1. The access point or AP.
2. The station or STA.

It is important to follow the order of the steps as failure to do so could render the routers inoperable.

Open a terminal and connect to this device over SSH. Make sure that this router has already been set up as a regular wireless access point and that wireless clients can connect to it fine. The procedure to do so is described at Enabling a Wi-Fi access point on OpenWrt.

Now, open the /etc/config/wireless configuration file and add the following line to the wifi-iface section in use by the access point for operational network functionality:

option wds '1'

Note that there may be multiple wifi-iface sections in this file, especially if the router is a dual-band device, in which case you need to ensure that you are editing the correct section.

This is an example of the /etc/config/wireless file on an access point for the 2.4 GHz band:

/etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/ahb/18100000.wmac'
	option band '2g'
	option country 'US'

config wifi-iface 'wifinet1'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'My WiFi'
	option encryption 'psk2'
	option key 'MyWiFiPassword'
	option wds '1'

Once that is done, save the file and reboot the device to apply the new network settings. Make sure that wireless clients are able to connect to this wireless access point and access the internet as well as they did with the old network configuration.

The ip address command should display a new network interface whose name is in the form of: “wlan.staN”; where N is a number. This new interface must exist alongside the base “wlanN” wireless network interface. For example, if you get the “wlan.sta1” network interface, the base interface is “wlan1”.

Note: when tested on Barrier Breaker, there was no new interface created, neither on the AP nor on the STA, despite WDS working properly.

Note: The new wlan.staN interface will not be bridged by default with the originating WLAN interface if that interface is not itself part of a bridge. To correct this problem, you will need to create a new bridge interface in the wireless access point and associate only its WLAN interface to it.

Initially, you might need to use an Ethernet cable to connect directly to the repeater and configure it. Open a terminal and connect to this device over SSH.

There are some important settings on the repeater to take into account before creating the wireless link between the repeater and the access point. For starters, the repeater must have its DHCP server disabled (assuming there is already a different DHCP server working on the network). On fresh-installs of OpenWrt, the DHCP server is usually enabled by default on the LAN interface, so to disable it you need to change the network settings of the repeater.

Open the /etc/config/dhcp file and add the following line to the config dhcp 'lan' section:

option ignore '1'

This line will disable the DHCP server on the LAN interface. The DHCP server should be already disabled on the WLAN interface, so save and close the file.

Note: On Chaos Calmer 15.05 / LuCI (git-15.248.30277-3836b45), the DHCP6 server had to be disabled as well, by changing option dhcpv6 'server' to option dhcpv6 'disabled'.

Now, you need to assign a network address other than the default static IP assignment of 192.168.1.1/24 to the LAN interface, if it is already being used by a different device on your network. Open the /etc/config/network file and change the IP address to one from the same subnet. For example, to 192.168.1.2/24. This is an example of the configuration file:

/etc/config/network

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'eth0.1'

config interface 'lan'
	option device 'br-lan'
	option proto 'static'
	option ipaddr '192.168.1.2'
	option netmask '255.255.255.0'

Alternatively, you may want to configure the repeater to fetch an IP address via DHCP from the access point, but that may leave the repeater inaccessible if the WDS connection does not work and it becomes unable to configure its network settings with DHCP. You would need to set the interface protocol to DHCP:

/etc/config/network

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'eth0.1'

config interface 'lan'
	option device 'br-lan'
	option proto 'dhcp'

Reboot the repeater to apply the new network settings. After it has restarted, remember to reconnect to the repeater via SSH on its new IP address. Keep in mind that the DHCP server is now disabled on its LAN network interface, so you might need to set a static IP address and subnet mask on the device you are using to configure the repeater.

Note: If you have set the LAN interface to use a dynamic IP address (DHCP client), you will need to search for the repeater's IP address every time you reboot it.

It is time to setup the actual wireless link. Open the /etc/config/wireless file and make sure the corresponding settings in the radioN section (where N is a number) match the values in the same file of the access point. For example, to use the same band and country code.

Additionally, in this file, modify the wifi-iface section to set it in “sta” (client) mode, include the desired SSID to which to connect (the one broadcasted by the access point) and ensure WDS is enabled by setting this value to 1. The specific options may be different depending on the hardware but the SSID, channel, encryption type and password must match the access point, and WDS mode must be turned on.

If you want to enable wireless access to the repeater and, therefore, to the main network and the Internet, which you might want to do if your use case is expanding the Wi-Fi coverage on your location, an additional wireless interface (wifi-iface) is required in this file. Copy over the previous wifi-iface and:

• Change the mode from sta to ap.
• Remove the option wds '1' line.

In this new Wi-Fi interface on the repeater, the SSID and the secret key may be the same as the access points to allow transparent roaming, but they can also be different. As long as you connect this new interface to the LAN network, which is the default, your other wireless devices connecting through this AP will also be seen as part of the big network.

This is an example of the /etc/config/wireless configuration file on a repeater for the 2.4 GHz band.

/etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/ahb/18100000.wmac'
	option band '2g'
	option country 'US'

config wifi-iface 'wifinet1'
	option device 'radio0'
	option network 'lan'
	option mode 'sta'
	option ssid 'My WiFi'
	option encryption 'psk2'
	option key 'MyWiFiPassword'
	option wds '1'

config wifi-iface 'wifinet2'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'My WiFi'
	option encryption 'psk2'
	option key 'MyWiFiPassword'

See the Configure Wi-Fi encryption wiki page for a reference on how to specify encryption and keys.

Disconnect the repeater from the wired network and reboot it, for example, by using its power button.

The repeater should boot and connect automatically to the access point wirelessly via WDS. It may take a few minutes for the repeater to associate and connect to the access point. Once this has happened, and if you decided to enable the DHCP client on the LAN interface (dynamic address), the wired interface of the repeater should succeed in getting a DHCP address through the new wireless backhaul connection. The wireless interface on the repeater does not get an IP address as it is now acting as a transparent bridge.

Any client devices connected to the repeater via an Ethernet cable (wired clients) should now be transparently connected into the main network over the wireless (WDS) link.

Everything shown in the command-line configuration with SSH section should be reproducible using LuCI in OpenWrt.

For the wireless access point, just set the wireless mode to “Access Point (WDS)” (screenshot)

On the LAN network interface of the repeater, change the default IP to a different one from the same subnet and disable the DHCP server. (screenshot)

For a wireless interface working on the same frequency band as the access point, click Scan, join the previously created wireless network and when asked, set the firewall zone to lan.

The wireless mode should be Client (WDS) and the Network in Interface Configuration has to be changed from wwan to lan. (screenshot)

Go to Network, DHCP and DNS. Set DNS forwardings to the IP address of the access point.

Go to Network, Interfaces, Lan, Edit. Set IPv4 gateway to the IP address of the access point.

Go to Network, Interfaces, Devices tab, Configure... on br-lan, Advanced device options and enable STP. Failing to do so can allow a network loop to form that will take down all routers.

Finally, add a new Wi-Fi network if you want to enable wireless access to the network. It can have the same name (SSID), password and settings than the access point, to allow transparent roaming, or they can be different. When creating the new Wi-Fi network, under General Setup, ensure that Mode is Access Point and Network is set to lan.

Relevant configuration files:

• /etc/config/wireless
• /etc/config/firewall
• /etc/config/dhcp

Multiple WDS Stations can connect to a single WDS Access Point.

• On the access point, add option wds '1' to the existing wifi-iface section and proceed with configuring SSID, channel, encryption etc.
• On the client, set option mode 'sta' and add option wds '1' to the wifi-iface section. Disable the DHCP server by adding option ignore '1''' for the LAN interface in /etc/config/dhcp.
• To create a repeater, add a WDS access point along with the WDS station on the client (with the same ssid and key, or not). Do not forget to add the newly created AP to the LAN firewall Zone.

On MAC80211, OpenWrt uses 4 address (option wds 1) (with ap or sta mode) and not repeater mode.