EDIT, just read your comment about losing connection, it is therefor wise to alter the OpenWrt auto DHCP client config to a static ip config first!
Although you lost connectivity IP-wise, you still can access and edit the netbook keyboard shell the wan settings
config interface 'wan' #keep wan
option device 'br-lan'
option proto 'static' #notice change back from dhcp > static ?
option ipaddr '192.168.43.139'
option netmask '255.255.255.0'
# option ip6assign '60'
option gateway '192.168.43.1'
option dns '220.127.116.11'
Makes settings active with:
/etc/init.d/network restart or
reboot whole router.
However if you wifi adapter in windows drop connection it will break the bridge and you will be locked out again... cannot fix this.... Understand that these IP-address change if you used bridged or ICS nat in Windows. So I guess that if you use ICS nat in windows the gateway ip becomes the ip of the windows laptop ics interface itself and netbook openwrt router ip changes accordingly.
So we/you just finished Option1 having internet on a OpenWrt router using the WAN interface and doing minimal commandline/nano editing to accomplish this, also a little bit of firewall rule editing made most common things available again.
This was kind of simple using DHCP, another variant would be using static ip addressing. I would really recommend you to also try that and maybe even Option2 discussed earlier where OpenWrt internet via its LAN interface. But this can all be done later, first you want progress...
My crystal ball stops here since I don't know exactly which interfaces or wifi modules or even firmware is needed. Therefor you have to read back and follow the USB live linux desktop distro boot on the netbook to gather info?
If you type
uname -a on the router it gives you the current linux version. This currently for 18.104.22.168 is somewhat the same as ubuntu 20.04.1.
Try to boot the
https://cdimage.ubuntu.com/ubuntu-mate/releases/20.04/release/ubuntu-mate-20.04.4-desktop-amd64.iso and see with:
dmesg #before plugging in USB wifi and after
lsmod #before plugging in USB wifi and after
Which modules are in use for your mini-pci-e intel wifi or usb realtek wifi. Than try with opkg update and install to fill the gaps.
If you don't want the live linux desktop distro, try to install with opkg packages like
opkg install pciutils usbutils wireless-tools wpa-supplicant whateverintelwifikmodmodule
If you have the right module for interface wifi driver or firmware, which can be discoverd with
ifconfig -a and
iwlist/iw scan interfacename you need a wireless network stack configuration tool as in. You only need wpasupplicant and no other tools if you are only using the wifi-client mode. To conclude your answer, before all this works you may append 'luci' variants of the cli tools to make it all work.
example stuff for wifi mac80211 cfg80211 hostap wpad