Realtek RTL8821CU Driver Source
This driver source has been modified as extensively as possible for stability.
git clone https://github.com/wildy623/Realtek-RTL8821CU.git
cd Realtek-RTL8821CU
bash install.sh
then reboot your device
run this command
usb_modeswitch -KW -v 0bda -p 1a2b
nano /lib/udev/rules.d/40-usb_modeswitch.rules
ATTR{idVendor}=="1234", ATTR{idProduct}=="5678", RUN+="/usr/sbin/usb_modeswitch -K -v 1234 -p 5678"
Make sure you change the ATTR id vendor value from default to the actual idVendor value, and also ensure that the idProduct value matches the output in lsusb.
Bus 001 Device 002: ID 0bda:1a2b Realtek Semiconductor Corp. RTL8188GU 802.11n WLAN Adapter (Driver CDROM Mode)
then in my configuration should like this
ATTR{idVendor}=="0bda", ATTR{idProduct}=="1a2b", RUN+="/usr/sbin/usb_modeswitch -K -v 0bda -p 1a2b"