After commenting out this section, I recompiled the xradio_wlan.ko module driver and retested.
After running 11 the OrangePi Zeros with the new xradio driver, connected to a router which changes its channel occasionally when multiple devices are connected, 5 OPis stop responding.
I ran the test overnight. I tested after connecting all OPis through the serial port (COM).
@zador.blood.stained @Tido @martinayotte any idea how I can further test the driver to stop the kernel hang?
p.s: I am ok with the dropped packets of the driver.