Arch Linux (kernel 5.4)
Arch Linux (kernel 5.9)
Linux Mint 20.1 (Linux Mint based on Ubuntu) (kernel 5.4)
Linux Mint 20 (Linux Mint based on Ubuntu) (kernel 5.4)
Linux Mint 19.3 (Linux Mint based on Ubuntu) (kernel 5.4)
LMDE 4 (Linux Mint based on Debian) (kernel 4.19)
Manjaro 20.1 (kernel 5.9)
Raspberry Pi OS (2021-01-11) (ARM 32 bit) (kernel 5.4)
Ubuntu 20.10 (kernel 5.8)
Ubuntu 20.04 (kernel 5.4)
Ubuntu 18.04 (kernel 5.4)
Note: Cudy does a good job of posting updated source code from Realtek. Support those who support us.
Note: Some adapter makers change the chipsets in their products while keeping the same model number so please check to confirm that the product you plan to buy has the chipset you are expecting.
The installation instructions are for the novice user. Experienced users are welcome to alter the installation to meet their needs.
Temporary internet access is required for installation. There are numerous ways to enable temporary internet access depending on your hardware and situation. One method is to use tethering from a phone.
Another method to enable temporary internet access is to keep an ultra cheap wifi adapter that uses an in-kernel driver in your toolkit.
You will need to use the terminal interface. The quick way to open a terminal: Ctrl+Alt+T (hold down on the Ctrl and Alt keys then press the T key)
DKMS is used for the installation. DKMS is a system utility which will automatically recompile and install this driver when a new kernel is installed. DKMS is provided by and maintained by Dell.
It is recommended that you do not delete the driver directory after installation as the directory contains information and scripts that you may need in the future.
Step 1: Open a terminal (Ctrl+Alt+T)
Step 2: Update the system (select the option for the OS you are using)
Option for Debian based distributions such as Ubuntu, Linux Mint and the Raspberry Pi OS
$ sudo apt-get update
Option for Arch based distributions such as Manjaro
$ sudo pacman -Syu
Step 3: Install the required packages (select the option for the OS you are using)
Option for Raspberry Pi OS
$ sudo apt-get install -y raspberrypi-kernel-headers bc build-essential dkms git
Option for LMDE (Debian based)
$ sudo apt-get install -y linux-headers-$(uname -r) build-essential dkms git
Option for Linux Mint or Ubuntu (all flavors)
$ sudo apt-get install -y dkms git
Option for Arch based distributions such as Manjaro
$ sudo pacman -S --noconfirm linux-headers dkms git
Step 4: Create a directory to hold the downloaded driver
$ mkdir src
Step 5: Move to the newly created directory
$ cd ~/src
Step 6: Download the driver
$ git clone https://github.com/morrownr/8821cu.git
Step 7: Move to the newly created driver directory
$ cd ~/src/8821cu
Step 8: Run a preparation script if required (Raspberry Pi hardware requires a preparation script)
Option for 32 bit operating systems to be installed to Raspberry Pi hardware
$ sudo ./raspi32.sh
Option for 64 bit operating systems to be installed to Raspberry Pi hardware
$ sudo ./raspi64.sh
Step 9: Run the installation script
$ sudo ./install-driver.sh
Step 10: Reboot
$ sudo reboot
A file called 8821cu.conf will be installed in /etc/modeprob.d by default.
Location: /etc/modprobe.d/8821cu.conf
This file will be read and applied to the driver on each system boot.
To edit the driver options file, run the edit-options.sh script.
$ sudo ./edit-options.sh
The driver options are as follows
Log level options ( rtw_drv_log_level )
0 = NONE (default) 1 = ALWAYS 2 = ERROR 3 = WARNING 4 = INFO 5 = DEBUG 6 = MAX
Note: You can save a log of RTW log entries by running the following in a terminal:
$ sudo ./save-log.sh
LED control options ( rtw_led_ctrl )
0 = Always off 1 = Normal blink (default) 2 = Always on
VHT enable options ( rtw_vht_enable )
0 = Disable 1 = Enable (default) 2 = Force auto enable (use caution)
Notes:
Power saving options ( rtw_power_mgnt )
0 = Disable power saving 1 = Power saving on, minPS (default) 2 = Power saving on, maxPS
Note: 0 may be useful in unattended server setups or if dropouts are experienced.
Step 1: Open a terminal (Ctrl+Alt+T)
Step 2: Move to the driver directory
$ cd ~/src/8821cu
Step 3: Run the removal script
$ sudo ./remove-driver.sh
Step 4: Reboot
$ sudo reboot
Note: These are general recommendations based on years of experience but may not apply to your situation so testing to see if any help fix your problem is recommended.
Security: Use WPA2-AES. Do not use WPA or WPA2 mixed mode or TKIP.
Channel Width for 2.4G: Use 20 MHz fixed width. Do not use 40 MHz or 20/40 automatic.
Channel width for 5G: Using a 40 MHz fixed width may help in some situations.
Channels for 2.4G: Use 1 or 6 or 11. Do not use automatic channel selection.
Mode for 2.4G: Use G/N or B/G/N. Do not use N only.
Network names: Do not set the 2.4G Network and the 5G Network to the same name. Note: Many routers come with both networks set to the same name.
Power Saving: Set to off. This can help in some situations. If you try turning it off and you see no improvement then set it back to on so as to save electricity.
After making these changes, reboot the router.
Check the current setting
$ sudo iw reg get
If you get 00, that is the default and may not provide optimal performance.
Find the correct setting here: http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
Set it temporarily
$ sudo iw reg set US
Note: Substitute your country code if you are not in the United States.
Set it permanently
$ sudo nano /etc/default/crda Change the last line to read: REGDOMAIN=US
If connecting your USB WiFi adapter to a desktop computer, use the USB ports on the rear of the computer. Why? The ports on the rear are directly connected to the motherboard which will reduce problems with interference and disconnection that can happen with front ports that use cables.
If your USB WiFi adapter is USB 3 capable then you need to plug it into a USB 3 port.
If you use an extension cable and your adapter is USB 3 capable, the cable needs to be USB 3 capable.
Some USB WiFi adapters require considerable electrical current and push the capabilities of the power available via USB port. One example is devices that use the Realtek 8814au chipset. Using a powered multiport USB extension can be a good idea in cases like this.
Add the following line to /boot/config.txt
dtoverlay=disable-wifi
$ sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
Delete the relevant WiFi network block (including the ‘network=’ and opening/closing braces.
Press ctrl-x followed by ‘y’ and enter to save the file.
Reboot