8821cu-20210916/FAQ.md

7.8 KiB

FAQ

Secure Boot Information

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

Answer: This question often comes up after installing the driver to a system that has Secure Boot on. To test if there is a Secure Boot related problem, turn secure boot off in the system BIOS and reboot. If the driver works as expected after reboot, then the problem is likely related to Secure Boot.

What will increase my chances of having a sucessessful installation on a system that has Secure Boot on?

First and foremost, make sure Secure Boot is on when you initially install your Linux distro. If your Linux distro was installed with Secure Boot off, the easiest solution is likely to do a clean reinstallation with Secure Boot on.

Ubuntu is used as the example but other distros should be similar to one degree or another. During the installation there may be a box on one of installation pages that will appear if the installation program detects that Secure Boot is on. You will need to check the appropriate box and supply a password. You can use the same password that you use for the system if you wish. After the installation and reboot completes, the first screen you should see is the mokutil screen. Mokutil will guide you through the process of setting up your system to support Secure Boot. If you are unsure what to do, I recommend you seek guidance from your distro documentation or user forums. Having Secure Boot properly set up in your installation is very important.

The install-driver.sh script currently supports Secure Boot if dkms is installed. Here is a link to the dkms website. There is information regarding Secure Boot in two sections in the README.

https://github.com/dell/dkms

Here is a link regarding Debian and Secure Boot:

https://wiki.debian.org/SecureBoot

If you are using a basic command line (non-dkms) installation, see the following section in the Installation Steps part of the README:

If you use the install-driver.sh script and see the following message

SecureBoot enabled - read FAQ about SecureBoot

You need to read the following:

The MOK managerment screen will appear during boot:

`Shim UEFI Key Management"

Press any key...

Select "Enroll key"

Select "Continue"

Select "Yes"

When promted, enter the password you entered earlier.

If you enter the wrong password, your computer will not be bootable. In this case, use the BOOT menu from your BIOS to boot then as follows:

sudo mokutil --reset

Restart your computer and use the BOOT menu from BIOS to boot. In the MOK managerment screen, select reset MOK list. Then Reboot and retry the driver installation.

Manual Installation Instructions

It provides secure boot instructions.


Question: Is WPA3 supported?

Answer: WPA3-SAE is supported. It works well on most modern Linux distros but not all. Generally the reason for WPA3 not working on Linux distros is that the distro has an old version of wpa_supplicant or Network Manager. Your options are to upgrade to a more modern distro such as those released after mid-2022 or compile and install new versions of wpa_supplicant and/or Network Manager.


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

Answer: 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.

Recommendation: If this is an important capability for you, I have tested Mediatek adapters for this capability and it does work with adapters that use the following chipsets: mt7921au, mt7612u and mt7610u.


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. Mediatek is making and supporting their drivers per Linux Wireless Standards guidance per the Linux Foundation. This results in far fewer compatibility and support problems. More information and recommended adapters shown at the following site:

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 may help.


Question: Can you provide additional information about monitor mode?

Answer: I have a repo that is setup to help with monitor mode:

https://github.com/morrownr/Monitor_Mode

Work to improve monitor mode is ongoing with this driver. Your reports of success or failure are needed. If you have yet to buy an adapter to use with monitor mode, there are adapters available that are known to work very well with monitor mode. My recommendation for those looking to buy an adapter for monitor mode is to buy adapters based on the following chipsets: mt7921au, mt7612u, mt7610u, rtl8821cu, and rtl8812bu. My specific recommendations for adapters in order of preference currently are:

ALFA AWUS036ACHM - long range - in-kernel driver

ALFA AWUS036ACM - in-kernel driver

ALFA AWUS036ACU - in-kernel driver (as of kernel 6.2) and out-of-kernel driver

To ask questions, go to USB-WiFi and post in Discussions or Issues.


Question: How do I forget a saved WiFi network on a Raspberry Pi?

Note: This answer is for the Raspberry Pi OS without Network Manager active.

Step 1: Edit wpa_supplicant.conf

sudo ${EDITOR} /etc/wpa_supplicant/wpa_supplicant.conf

Note: Replace ${EDITOR} with the name of the text editor you wish to use.

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

Step 3: Save the file.

Step 4: Reboot


Question: How do I disable the onboard WiFi in a Raspberry Pi?

Note: This answer is for the Raspberry Pi OS.

Answer:

Add the following line to /boot/config.txt

dtoverlay=disable-wifi

Question: When running sudo sh install-driver.sh on my RasPi 4B or 400, I see the following:

Your kernel header files aren't properly installed.
Please consult your distro documentation or user support forums.
Once the header files are properly installed, please run...

Answer: The Pi 4/400 firmware now prefers the 64-bit kernel if one exists so even if you installed the 32 bit version of the RasPiOS, you may now have the 64 bit kernel active.

The fix:

add the following to /boot/config.txt and reboot:

arm_64bit=0

Reference:

https://forums.raspberrypi.com/viewtopic.php?p=2091532&hilit=Tp+link#p2091532

Note to RasPiOS devs: We really really wish you would consider the consequences of the changes you make. Thank you.


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

Answer: There appears to be an issue that is caused by makers setting up adapters differently. 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.