I’ve got a Speedtouch 121g wifi stick which internally is a Intersil ISL3887.
USB: 06B9:0121 Alcatel Telecom SpeedTouch 121g Wireless Dongle
It works, with the firmware from here:
But deauths after random time.
From what I have read I should disable IPV6, and connect to a powered usb hub.
I both tried that but it still goes offline after a while. Only ifup wlan0 reactivates it (through UART)
Running Dietpi v129
Screenshots with the deauth message: