OpenWRT & Mediatek WiFi USB adapters
I was experimenting with two cheap Mediatek USB WiFi adapters in OpenWRT and had to experiment until I figured out which kmods were necessary to make it work, so documenting here in case someone else has the same issue…
Hardware
First up, the adapters, you can find these on Aliexpress by searching for
mt7921au
or similar. They are both quite cheap (~5 USD and ~10 USD) and work
out of the box in most normal Linux distributions – but not OpenWRT!
Noname 1800Mbps WiFi 6 USB Adapter 802.11AX:

EDUP 3000Mbps WiFi 6E Wireless Network Card USB:

Software
The packages required for making them work is:
kmod-mt7921-firmware
kmod-mt7921u
I just added these under “Customize installed packages and/or first boot script” at the OpenWRT firmware selector, in my case for the Raspberry Pi 4B.
In my case I also wanted to use a special networking setup so I googled my way into a configuration I yolo’ed into “Script to run on first boot (uci-defaults)” at the same page. I wanted to disable dhcp and I wanted two VLAN interfaces. I then burned the generated factory image to a sd card and put into my Raspberry Pi 4B.
exec >/tmp/setup.log 2>&1
uci set network.lan.proto="dhcp"
uci set network.wifi="interface"
uci set network.wifi.device="eth0.100"
uci set network.wifi.proto="none"
uci set network.iot="interface"
uci set network.iot.device="eth0.200"
uci set network.iot.proto="none"
uci commit network
/etc/init.d/network restart
uci delete firewall.vlan100
uci delete firewall.vlan200
uci delete dhcp.lan
uci commit firewall
uci commit dhcp
/etc/init.d/firewall restart
echo "All done!"