For years I have struggled getting my Realtek Semiconductor Corp. 802.11AC NIC USB stick to work on Linux. Below are how to enable these drivers. I got the wireless USB stick on eBay and it comes with an install disk. But the installation was just too technical. Below are the how to terminal commands to enable this. Now I can enjoy the 200GB download speeds my ISP is providing. Enjoy.
Note: For my Realtek Semiconductor Corp. 802.11AC NIC USB stick, the commands are:
sudo apt update
sudo apt install build-essential git dkms
git clone https://github.com/brektrou/rtl8821CU.git
cd rtl8821CU
chmod +x dkms-install.sh
sudo ./dkms-install.sh
sudo modprobe 8821cu
Source: https://forums.linuxmint.com/viewtopic.php?t=324111
Source: https://forums.linuxmint.com/viewtopic.php?t=324111
