-----

#### Click [here](https://github.com/morrownr/USB-WiFi) for USB WiFi Adapter Information for Linux

-----

#### A FAQ is available at the end of this document.

-----

#### Problem reports go in `Issues`. Include the information obtained with:

```
sudo uname -a; mokutil --sb-state; lsusb; rfkill list all; dkms status; iw dev
```

-----

## 8821cu ( 8821cu.ko ) :rocket:

## Linux Driver for USB WiFi Adapters that are based on the RTL8811CU, RTL8821CU and RTL8731AU Chipsets

- v5.12.0 (Realtek) (20210118) plus updates from the Linux community
- 1,300+ Views over the 2 weeks ended on 20220606 (Thank you!)

### Features

- IEEE 802.11 b/g/n/ac WiFi compliant
- 802.1x, WEP, WPA TKIP and WPA2 AES/Mixed mode for PSK and TLS (Radius)
- WPA3 (see FAQ)
- IEEE 802.11b/g/n/ac Client mode
  * Supports wireless security for WEP, WPA TKIP and WPA2 AES PSK
  * Supports site survey scan and manual connect
  * Supports WPA/WPA2 TLS client
- Power saving modes
- Wireshark compatible
- Aircrack-ng compatible
- Packet injection
- hostapd compatible
- AP mode DFS channel support
- Miracast
- Supported interface modes
  * IBSS
  * Managed
  * Monitor
  * AP
  * P2P-client
  * P2P-GO
  * Concurrent (see `Concurrent_Mode.md` in the `docs` folder.)
- Log level control
- LED control
- Power saving control
- VHT control (allows 80 MHz channel width in AP mode)
- AP mode DFS channel control

### Compatible CPUs

- x86, amd64
- ARM, ARM64

### Compatible Kernels

- Kernels: 4.19 - 5.11 (Realtek)
- Kernels: 5.12 - 6.0  (community support)

### Tested Linux Distributions

Note: One of the goals of this project is to provide driver support that
is easy to install and works reliably on many distros. Meeting this goal
depends on you to report your recommendations and updated information. 
If you see information that needs to be updated, please report the
updated information and if you do not see adequate support for
items such as Installation Steps 2, 3 and 9, and you know what updates 
need to added or you can get that information, please provide it so that
the Installation Steps can be improved.

- Arch Linux (kernels 5.4 and 5.11)

- Fedora (kernel 5.11)

- Debian 11 (kernels 5.10 and 5.15)

- Kali Linux (kernel 5.10)

- Manjaro 20.1 (kernel 5.9) and 21.1 (kernel 5.13)

- openSUSE Tumbleweed (rolling) (kernel 5.15)

- Raspberry Pi OS (2022-04-04) (ARM 32 bit and 64 bit) (kernel 5.15)

- Raspberry Pi Desktop (x86 32 bit) (kernel 4.19)

- Solus

- Ubuntu 22.04 (kernel 5.15)

### Download Locations for Tested Linux Distributions

- [Arch Linux](https://www.archlinux.org)
- [Debian](https://www.debian.org/)
- [Fedora](https://getfedora.org)
- [Kali Linux](https://www.kali.org/)
- [Manjaro](https://manjaro.org)
- [openSUSE](https://www.opensuse.org/)
- [Raspberry Pi OS](https://www.raspberrypi.org)
- [Solus](https://getsol.us/home/)
- [Ubuntu](https://www.ubuntu.com)

### Tested Hardware

- [EDUP EP-AC1651 USB WiFi Adapter AC650 Dual Band USB 2.0 Nano](https://www.amazon.com/gp/product/B0872VF2D8)
- [EDUP EP-AC1635 USB WiFi Adapter AC600 Dual Band USB 2.0](https://www.amazon.com/gp/product/B075R7BFV2)


### Compatible Devices

* Cudy WU700
* BrosTrend AC5L
* EDUP EP-AC1651
* EDUP EP-AC1635
* TOTOLINK A650UA v3
* Mercusys MU6H (multi-state)
* Numerous additional products that are based on the supported chipsets

Note: Please read "supported-device-IDs" for information about how to confirm the correct driver for your adapter.

### Installation Information

Warning: Installing multiple drivers for the same hardware usually does
not end well. If a previous attempt to install this driver failed or if
you have previously installed another driver for chipsets supported by
this driver, you MUST remove anything that the previous attempt
installed BEFORE attempting to install this driver. This driver can be
removed with the script called `./remove-driver.sh`. Information is
available in the section called `Removal of the Driver.` You can get a
good idea as to whether you need to remove a previously installed
driver by running the following command:

```
sudo dkms status
```

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.](https://www.makeuseof.com/tag/how-to-tether-your-smartphone-in-linux).
Another method is to keep a [WiFi adapter that uses an in-kernel driver](https://github.com/morrownr/USB-WiFi) 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).

An alternative terminal is to use SSH (Secure Shell) from the same or from
another computer, in which case you will be in a suitable terminal after logging
in, but this step requires that an SSH daemon/server has already been
configured. (There are lots of SSH guides available, e.g., for the [Raspberry Pi](https://www.raspberrypi.com/documentation/computers/remote-access.html#setting-up-an-ssh-server) and for [Ubuntu](https://linuxconfig.org/ubuntu-20-04-ssh-server). Do not forget [to secure the SSH server](https://www.howtogeek.com/443156/the-best-ways-to-secure-your-ssh-server/).)

You will need to have sufficient access rights to use `sudo` so that commands
can be executed as the `root` user. (If the command `sudo echo Yes` returns
"Yes", with or without having to enter your password, you do have sufficient
access rights.)

DKMS is used for the installation. DKMS is a system utility which will
automatically recompile and reinstall 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.

Secure mode: The primary installation script, `install-driver.sh`, will support
secure mode... if your distro supports the method in use. I regularly test the installation
script on systems with secure mode on. It works very well on Ubuntu based distros. Some
distros, such as Raspberry Pi OS, do not support secure mode because the hardware they
support does not support secure mode making it unnecessary. There are distros that do not
work with the support currently in use with this driver. If you install this driver and,
after a reboot, the driver is not working, you can go into the BIOS and tempoarily turn
secure mode off to see if secure mode is the problem. I am currently investigating alternative
ways to support secure mode that will work on most or all distros that support secure mode.
If you are interested in helping, please post a message in `Issues`.

### Installation Steps

#### Step 1: Open a terminal (e.g. Ctrl+Alt+T)

#### Step 2: Update and upgrade system packages (select the option for the OS you are using)

Note: If your Linux distro does not fall into one of options listed
below, you will need to research how to update and upgrade your system
packages.

- Option for Debian based distributions such as Ubuntu, Linux Mint, Kali and Raspberry Pi OS

```
sudo apt update && sudo apt upgrade
```

- Option for Arch based distributions such as Manjaro

```
sudo pacman -Syu
```

- Option for Fedora based distributions

```
sudo dnf upgrade
```

- Option for openSUSE based distributions

```
sudo zypper update
```

Note: It is recommended that you reboot your system at this point. The
rest of the installation will appreciate having a fully up to date
system to work with. The installation can then be continued with Step 3.

```
sudo reboot
```

#### Step 3: Install the required packages (select the option for the OS you are using)

- Option for Raspberry Pi OS (ARM/ARM64)

```
sudo apt install -y raspberrypi-kernel-headers build-essential bc dkms git
```

- Option for Debian, Kali, and Raspberry Pi Desktop (x86)

```
sudo apt install -y linux-headers-$(uname -r) build-essential bc dkms git libelf-dev
```

- Option for Ubuntu (all official flavors) and the numerous Ubuntu based distros

```
sudo apt install -y build-essential dkms git 
```

- Option for Fedora

```
sudo dnf -y install git dkms kernel-devel kernel-debug-devel
```

- Option for openSUSE

```
sudo zypper install -t pattern devel_kernel dkms
```

- Option for Solus

```
sudo eopkg install gcc linux-current-headers make git binutils
```

- Options for Arch and Manjaro

If using pacman

```
sudo pacman -S --noconfirm linux-headers dkms git
```

Note: If you are asked to choose a provider, make sure to choose the one
that corresponds to your version of the linux kernel (for example,
"linux510-headers" for Linux kernel version 5.10). If you install the
incorrect version, you'll have to uninstall it and install the correct
version.

If using other methods, please follow the instructions provided by those
methods.

#### Step 4: Create a directory to hold the downloaded driver

```
mkdir -p ~/src
```

#### Step 5: Move to the newly created directory

```
cd ~/src
```

#### Step 6: Download the driver

```
git clone https://github.com/morrownr/8821cu-20210118.git
```

#### Step 7: Move to the newly created driver directory

```
cd ~/src/8821cu-20210118
```

#### Step 8: (optional) Enable Concurrent Mode ( cmode-on.sh )

Note: see `Concurrent_Mode.md` in the `docs` folder to help determine
whether you want to enable Concurrent Mode.

```
./cmode-on.sh
```

#### Step 9: Run a script to reconfigure for ARM or ARM64 based systems

Warning: This driver defaults to supporting x86 and amd64 based systems
and this step should be `skipped` if your system is powered by an x86, 
amd64 or compatible CPU.

Note: If your system is powered by an ARM or ARM64 based Raspberry Pi,
then one of the following scripts should be executed:

- Option for the following listed operating systems to be installed to
Raspberry Pi hardware

```
       * Raspberry Pi OS (32 bit)
```

```
./ARM_RPI.sh
```

- Option for the following listed operating systems to be installed to
Raspberry Pi hardware

```
       * Raspberry Pi OS (64 bit)
       * Kali Linux RPI ARM64
       * Ubuntu for Raspberry Pi
```

```
./ARM64_RPI.sh
```

Note: ARM or ARM64 based systems not listed above will likely require
modifications similar to those provided in the above scripts but the
number and variety of different ARM and ARM64 based systems makes
supporting each system unpractical so you will need to research the
needs of your system and make the appropriate modifications. If you
discover the settings and make a new script that works with your ARM or
ARM64 based system, you are welcome to submit the script and information
to be included here.

#### Step 10: Run the installation script ( install-driver.sh or install-driver-no-dkms.sh )

Note: For automated builds (non-interactive), use _NoPrompt_ as an option.

Option for distros that support `dkms` (almost all)

```
sudo ./install-driver.sh
```

Option for distros that do not support `dkms`

```
sudo ./install-driver-no-dkms.sh
```

Note: If you elect to skip the reboot at the end of the installation
script, the driver may not load immediately and the driver options will
not be applied. Rebooting is strongly recommended.

Manual build instructions: The scripts automate the installation process,
however, if you want to or need to do a command line installation, use
the following:

```
make clean
make
sudo make install
sudo reboot
```

Note: If you use the manual build instructions or the `install-driver-no-dkms.sh`
script, you will need to repeat the process each time a new kernel is
installed in your distro.

-----

### Driver Options ( edit-options.sh )

A file called `8821cu.conf` will be installed in `/etc/modprobe.d` by
default.

Note: The installation script will prompt you to edit the options.

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
```

Note: Documentation for Driver Options is included in the file `8821cu.conf`.

-----

### Removal of the Driver ( remove-driver.sh or remove-driver-no-dkms.sh )

Note: Removing the driver is advised in the following situations:

- if driver installation fails
- if the driver is no longer needed
- if a new or updated version of the driver needs to be installed
- if a distro version upgrade is going to be installed (i.e. going from kernel 5.10 to kernel 5.15)

Note: The following removes everything that has been installed, with the
exception of the packages installed in Step 3 and the driver directory.
The driver directory can be deleted after running this script.

#### Step 1: Open a terminal (e.g. Ctrl+Alt+T)

#### Step 2: Move to the driver directory

```
cd ~/src/8821cu-20210118
```

#### Step 3: Run the removal script

Note: For automated builds (non-interactive), use _NoPrompt_ as an option.

Option for distros that support `dkms` (almost all)

```
sudo ./remove-driver.sh
```

Option for distros that do not support `dkms`

```
sudo ./remove-driver-no-dkms.sh
```

-----

### Recommended WiFi Router/ Access Point Settings

Note: These are general recommendations, some of which may not apply to your specific situation.

- Security: Set WPA2-AES. Do not set WPA2 mixed mode or WPA or TKIP.

- Channel width for 2.4 GHz: Set 20 MHz fixed width. Do not use 40 MHz or 20/40 automatic.

- Channels for 2.4 GHz: Set channel 1 or 6 or 11 depending on the congestion at your location. Do not set automatic channel selection. As time passes, if you notice poor performance, recheck congestion and set channel appropriately. The environment around you can and does change over time.

- Mode for 2.4 GHz: For best performance, set "N only" if you no longer use B or G capable devices.

- Network names: Do not set the 2.4 GHz Network and the 5 GHz Network to the same name. Note: Unfortunately many routers come with both networks set to the same name. You need to be able to control which network that is in use so changing the name of one of the networks is recommended. Since many IoT devices use the 2.4 GHz network, it may be better to change the name of the 5 GHz network.

- Channels for 5 GHz: Not all devices are capable of using DFS channels (I'm looking at you Roku.) It may be necessary to set a fixed channel in the range of 36 to 48 or 149 to 165 in order for all of your devices to work on 5 GHz. (For US, other countries may vary.)

- Best location for the WiFi router/access point: Near center of apartment or house, at least a couple of feet away from walls, in an elevated location. You may have to test to see what the best location is in your environment.

- Check congestion: There are apps available for smart phones that allow you to check the congestion levels on WiFi channels. The apps generally go by the name of ```WiFi Analyzer``` or something similar.

After making and saving changes, reboot the router.

-----

### Recommendations regarding USB

- Moving your USB WiFi adapter to a different USB port has been known to fix a variety of problems.

- 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.

- If your USB WiFi adapter is USB 3 capable and you want it to operate in USB3 mode, plug it into a USB 3 port.

- Avoid USB 3.1 Gen 2 ports if possible as almost all currently available adapters have been tested with USB 3.1 Gen 1 (aka USB 3) and not with USB 3.1 Gen 2.

- If you use an extension cable and your adapter is USB 3 capable, the cable needs to be USB 3 capable (if not, you will at best be limited to USB 2 speeds).

- Extention cables can be problematic. A way to check if the extension cable is the problem is to plug the adapter temporarily into a USB port on the computer.

- Some USB WiFi adapters require considerable electrical current and push the capabilities of the power available via USB port. One example is adapters that use the Realtek 8814au chipset. Using a powered multiport USB extension can be a good idea in cases like this.

-----

### How to disable onboard WiFi on Raspberry Pi 3B, 3B+, 3A+, 4B and Zero W

Add the following line to /boot/config.txt

```
dtoverlay=disable-wifi
```

-----

### How to forget a saved WiFi network on a Raspberry Pi

#### Step 1: Edit wpa_supplicant.conf

```
sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
```

#### Step 2: Delete the relevant WiFi network block (including the 'network=' and opening/closing braces.

#### Step 3: Press ctrl-x followed by 'y' and enter to save the file.

#### Step 4: Reboot

-----

### FAQ:

Question: Is WPA3 supported?

Answer: WPA3-SAE support is in this driver according to Realtek, however, for it
to work in client mode with some current Linux distros, you will need to
download, compile and install the current development version of wpa_supplicant
from the following site:

https://w1.fi/cgit/

Note: There is a file in the `docs` folder called `Update_wpa_supplicant_v3a.md`
that may help with updating wpa_supplicant.

Note: Some distros appear to have versions of Network Manager that are not
compatible with this driver. If that is the case, you may need to STOP or KILL
Network Manager and connect using wpa_supplicant.

WPA3-SAE is working well in AP mode using hostapd with current versions of the
Raspberry Pi OS.

-----

Question: I bought two rtl8811cu based adapters and am planning to use both in
the same computer. How do I set that up?

Answer: You can't without considerable technical skills.  Realtek drivers do not
support more than one adapter with the same chipset in the same computer. You
can have multiple Realtek based adapters in the same computer as long as the
adapters are based on different chipsets.

-----

Question: Why do you recommend Mediatek based adapters when you maintain this
repo for a Realtek driver?

Answer: Many new and existing Linux users already have adapters based on Realtek
chipsets. This repo is for Linux users to support their existing adapters but my
STRONG recommendation is for Linux users to seek out USB WiFi solutions based on
Mediatek chipsets:

https://github.com/morrownr/USB-WiFi

-----

Question: Will you put volunteers to work?

Answer: Yes. Post a message in `Issues` or `Discussions` if interested.

-----

Question: I am having problems with my adapter and I use Virtualbox?

Answer: This [article](https://null-byte.wonderhowto.com/forum/wifi-hacking-attach-usb-wireless-adapter-with-virtual-box-0324433/) may help.

-----

Question: The driver installation script completed successfully and the
driver is installed but does not seem to be working. What is wrong?

Answer: Turn secure boot off to see if that allows the driver to work.
This driver is primarily tested on Debian based distros such as Ubuntu,
Raspberry Pi OS and Kali. In an attempt to make this driver work well on
many Linux distros, other distros, including the Arch based Manjaro is
used for testing. Currently I do not have installations of Fedora or
OpenSUSE available for testing and reply on user reports of success or
failure. I have two test systems with secure boot on so as to test secure
boot. I have not seen any secure boot problems with Debian based systems
and I don't remember problems with Manjaro.

dkms is used in the installation script. It helps with a lot of issues that
will come up if a simple manual installation is used. dkms has the
capability to handle the needs of secure boot. dkms was written by and is
maintained by Dell. Dell has been offering some Ubuntu pre-loaded systems
for years so their devs likely test on Ubuntu. I suspect Fedora and
OpenSUSE may be handing their secure boot support differently than Debian
based systems and this is leading to problems. This and the other repos
I have are VERY heavily used and I am sure there are plenty of non-Debian
users that use this driver. Are they all turning off secure boot and not
reporting the problem? I don't know. What I do know is that reports like
this are rare.

For the driver to compile and install correctly but not be available
tells me there is likely a key issue. Here is an interesting link
regarding Debian systems and secure boot:

https://wiki.debian.org/SecureBoot

That document contains a lot of information that can help an investigation
into what the real problem is and I invite you and other Fedora, OpemSUSE
and users of other distros that show this problem to investigate and
present what you know to the devs of your distro via their problem
reporting system. Turning off secure boot is NOT a fix. A real fix needs
to happen.


-----

Question: I have an adapter with the 8821cu chipset which means it supports
bluetooth. The bluetooth works but the wifi does not. What is wrong?

Answer: There appears to be a hardware bug in some 8821cu based adapters
and the fix is to set the driver option ( `rtw_RFE_type` ) in 8821cu.conf.
The easiest way to edit 8821cu.conf is to run the following from the driver
directory:

```
sudo ./edit-options.sh
```

Once in the document, you can scroll down to the documentation about
`rtw_RFE_type`. You will likely have to experiment to find out what setting
works best for your adapter but a good place to start is probably...

```
rtw_RFE_type=7
```

Simply add that option to the end of the `options` line, save and reboot.

-----

