Wi-Fi Extender/Repeater with STA (client) link to upstream AP (Hotspot)

This is by far the simplest means of extending Wi-Fi coverage. It does not require any changes to the upstream access point.
It is sometimes referred to as “wi-fi tethering”.

AP+STA mode allows OpenWrt to connect to a wireless hotspot (AP) and provide wireless access from that hotspot to anything connected to the OpenWrt AP and Ethernet ports, the br-lan device. This assumes that your OpenWrt device has the default settings where the AP and Ethernet port are bridged.

The changes below assume an OpenWrt default configuration, the relevant files are:

cp /etc/config/firewall /etc/config/firewall.bak
cp /etc/config/network /etc/config/network.bak
cp /etc/config/wireless /etc/config/wireless.bak
cp /etc/config/dhcp /etc/config/dhcp.bak
# Add WWAN network to WAN zone
uci add_list firewall.@zone[1].network="wwan"
uci commit firewall
/etc/init.d/firewall restart
# Change the default OpenWrt IP address
# Note that OpenWrt AP IP address must be in a different subnet than the hotspot (AP) IP address.
uci set network.lan.ipaddr=""
# Add the WWAN interface
uci set network.wwan="interface"
uci set network.wwan.proto="dhcp"
uci commit network
/etc/init.d/network restart
# Add a Wi-Fi interface
uci set wireless.wwan="wifi-iface"
uci set wireless.wwan.device="radio0"
uci set wireless.wwan.network="wwan"
uci set wireless.wwan.mode="sta"
# The encryption and ssid values need to match those of the hotspot (AP)
uci set wireless.wwan.encryption="none"
uci set wireless.wwan.key="super_secret_key"
uci set wireless.wwan.ssid="hotspot or AP ssid"
uci commit wireless
wifi reload

:!: An alternative event-driven recovery solution is to be found here.

When the hotspot is not available or it is incorrectly defined in the wireless configuration file, OpenWrt will disable the AP. This means that you can only access your OpenWrt device through its Ethernet port. The following will describe how to get OpnWrt to test for the hotspot availability after boot. If OpenWrt can not connect to the hotspot after 30 seconds, OpenWrt will automatically reconfigure itself to AP Only mode. This will allow wireless access to your OpenWrt device again.

# Create AP Only and AP+STA wireless configuration files
cp /etc/config/wireless.original /etc/config/wireless.ap-only
cp /etc/config/wireless /etc/config/wireless.ap+sta
# Install the necessary packages
opkg update
opkg install iwinfo
# Save the script
cat << "EOF" > /usr/local/bin/fix_sta_ap.sh
# Fix loss of AP when STA (Client) mode fails by reverting to default
# AP only configuration. Default AP configuration is assumed to be in
# /etc/config/wireless.ap-only
while [ $(iwinfo | grep -c "ESSID: unknown") -ge 1 ]; do
   let sta_err=$sta_err+1
   if [ $((sta_err * SLEEP)) -ge $TIMEOUT ]; then
     cp /etc/config/wireless.ap-only /etc/config/wireless
     wifi up
#    uncomment the following lines to try AP+STA after reboot
#    sleep 3
#    cp /etc/config/wireless.ap+sta /etc/config/wireless
   sleep $SLEEP
# Make the script executable
chmod +x /usr/local/bin/fix_sta_ap.sh
# Configure autostart
sed -i -e "
\$i /usr/local/bin/fix_sta_ap.sh > /dev/null &
" /etc/rc.local

In one place there may be several Hotspots that may be available or not according to the comings and goings of their owners; we will enter the parameters of each one of them in the configuration file therefore wwanHotspot will connect and disconnect the OpenWrt HotSpot client to one of them as they become available.

This daemon may be used instead of the method described in step 3. Download the latest version of wwanHotspot and follow the instructions.

Disable DNS rebind protection if you need to trust upstream resolvers.

uci set dhcp.@dnsmasq[0].rebind_protection="0"
uci commit dhcp
/etc/init.d/dnsmasq restart
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  • Last modified: 2024/06/24 09:37
  • by bluewavenet