[SOLVED] (RTL8821CU-CG) Wireless adapter installed, detected but not working

[FamCompKid]

Hi,

My wireless adapter arrived today and I'm stuck. (Last week I made a separate "I have no idea" post about this but I thought this needed another post; sorry if a new post shouldn't be the case.)

Wireless adapter is on RTL8821CU-CG, dual-band, and has bluetooth. (Here's its product page and its driver page if it helps.)

I followed this advice:

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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

It was all good except that the wireless adapter didn't turn on (it has a green light indicator), so I rebooted.

After reboot, bluetooth turned on and I tried it and it worked, detected a phone.

But I can't see any signs of it being able to connect to WiFi.

I went to https://github.com/brektrou/rtl8821CU to consult.

lsusb returns (I removed irrelevant text):

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Bus 003 Device 016: ID 0bda:c820 Realtek Semiconductor Corp. 

Author says (removed irrelevant text):

switch the mode by type: (the device ID must be yours.)

Need install usb_modeswitch

sudo usb_modeswitch -KW -v 0bda -p 1a2b

It should work.

Based on my lsusb, I did this:

sudo usb_modeswitch -KW -v 0bda -p c820

But it returns this:

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Take all parameters from the command line

 * usb_modeswitch: handle USB devices with multiple modes
 * Version 2.5.2 (C) Josua Dietze 2017
 * Based on libusb1/libusbx

 ! PLEASE REPORT NEW CONFIGURATIONS !

DefaultVendor=  0x0bda
DefaultProduct= 0xc820

StandardEject=1

Look for default devices ...
  found USB ID 8087:8000
  found USB ID 1d6b:0002
  found USB ID 8087:8008
  found USB ID 1d6b:0002
  found USB ID 1d6b:0003
  found USB ID 1c4f:0026
  found USB ID 093a:2510
  found USB ID 0bda:c820
   vendor ID matched
   product ID matched
  found USB ID 04e8:6863
  found USB ID 1d6b:0002
 Found devices in default mode (1)
Access device 016 on bus 003
Get the current device configuration ...
Current configuration number is 1
Use interface number 0
 with class 224
Error: can't use storage command in MessageContent with interface 0; interface class is 224, expected 8. Abort

I think I understand what it says but of course I have no idea what to do

Many thanks in advance!

[sleeper12]

Try this, one line at a time:

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sudo apt install build-essential -y
mkdir -p ~/build
cd ~/build
sudo apt install git
git clone https://github.com/brektrou/rtl8821CU.git
cd rtl8821CU
make
sudo make install 

Reboot

[FamCompKid]

Thank you, but I believe nothing happened, except that Bluetooth auto-started (an icon on the panel) but was disabled.

Just noting:

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~/build$ git clone https://github.com/brektrou/rtl8821CU.git
fatal: destination path 'rtl8821CU' already exists and is not an empty directory.

... but all the other commands went ok, I think. Just had to skip that one above.

Just also want to share this comment on Github from someone who ordered twice the same model of adapter that I have.

Have to go to bed now. TIA again. Will see this first thing tomorrow.

[sleeper12]

Could Bluetooth be blocking wifi? See #1.4.3 here:
https://easylinuxtipsproject.blogspot.c ... ml#ID1.4.3

[FamCompKid]

Hi and thanks again. After reboot, bluetooth remains disabled. This means I don't need to disable it in BIOS anymore, correct?

[FamCompKid]

I followed this advice:

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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

Also, question: Why is it preferred to install from ones like the above? Is it because they're regularly updated? Can we not use the driver that comes with this particular adapter?

[FamCompKid]

I'm manually copying this from the desktop (I'm on laptop), hope it helps.

dkms status returns:

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rtl8821CU, 5.4.1, 5.4.0-52-generic, x86_64: installed (WARNING! Diff between built and installed module!) 

[sleeper12]

Is wifi working now or still not?

[FamCompKid]

It's still not working, thank you.

[sleeper12]

Let's see:

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 inxi -Fxxxz && rfkill list && mokutil --sb-state 

[FamCompKid]

EDIT: Updated with mokutil installed

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~$ inxi -Fxxxz && rfkill list && mokutil --sb-state
System:    Host: *** Kernel: 5.4.0-52-generic x86_64 bits: 64 compiler: gcc v: 7.5.0 Desktop: Cinnamon 4.4.8 
           wm: muffin 4.4.4 dm: LightDM 1.26.0 Distro: Linux Mint 19.3 Tricia base: Ubuntu 18.04 bionic 
Machine:   Type: Desktop Mobo: MSI model: H81M-P33 (MS-7817) v: 1.0 serial: <filter> BIOS: American Megatrends v: 1.6 
           date: 07/01/2014 
CPU:       Topology: Quad Core model: Intel Core i5-4590 bits: 64 type: MCP arch: Haswell rev: 3 L2 cache: 6144 KiB 
           flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 26401 
           Speed: 800 MHz min/max: 800/3700 MHz Core speeds (MHz): 1: 800 2: 800 3: 800 4: 800 
Graphics:  Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics vendor: Micro-Star MSI 
           driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:0412 
           Display: x11 server: X.Org 1.19.6 driver: modesetting unloaded: fbdev,vesa resolution: 1366x768~60Hz 
           OpenGL: renderer: Mesa DRI Intel HD Graphics 4600 (HSW GT2) v: 4.5 Mesa 20.0.8 compat-v: 3.0 
           direct render: Yes 
Audio:     Device-1: Intel 8 Series/C220 Series High Definition Audio vendor: Micro-Star MSI driver: snd_hda_intel 
           v: kernel bus ID: 00:1b.0 chip ID: 8086:8c20 
           Sound Server: ALSA v: k5.4.0-52-generic 
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Micro-Star MSI driver: r8169 
           v: kernel port: e000 bus ID: 02:00.0 chip ID: 10ec:8168 
           IF: enp2s0 state: down mac: <filter> 
           Device-2: Samsung GT-I9500 [Galaxy S4] / GT-I9250 [Galaxy Nexus] (network tethering) type: USB 
           driver: rndis_host bus ID: 3-1:7 chip ID: 04e8:6863 serial: <filter> 
           IF: enp0s20u1 state: unknown speed: N/A duplex: N/A mac: <filter> 
Drives:    Local Storage: total: 931.51 GiB used: 301.64 GiB (32.4%) 
           ID-1: /dev/sda vendor: Western Digital model: WD10EZEX-08WN4A0 size: 931.51 GiB speed: 6.0 Gb/s 
           rotation: 7200 rpm serial: <filter> rev: 1A01 temp: 40 C scheme: MBR 
Partition: ID-1: / size: 915.89 GiB used: 301.64 GiB (32.9%) fs: ext4 dev: /dev/sda1 
Sensors:   System Temperatures: cpu: 41.0 C mobo: N/A 
           Fan Speeds (RPM): N/A 
Info:      Processes: 195 Uptime: 1h 00m Memory: 7.66 GiB used: 1.23 GiB (16.0%) Init: systemd v: 237 runlevel: 5 
           Compilers: gcc: 7.5.0 alt: 7 Shell: bash v: 4.4.20 running in: gnome-terminal inxi: 3.0.32 
0: hci0: Bluetooth
	Soft blocked: yes
	Hard blocked: no
EFI variables are not supported on this system

[JeremyB]

Any results for

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dmesg | grep -i rtw

[FamCompKid]

Any results for

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dmesg | grep -i rtw

Thank you, Jeremy.

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~$ dmesg | grep -i rtw
[   14.608573] 8821cu: unknown parameter 'rtw_led_ctrl' ignored

Before we go further, I've been thinking about upgrading to LM 20. Actually my plan was to sort out my WiFi issues here on LM 19.3 first but now I realize that may be a bad idea. I'll return this adapter if it doesn't work on LM 20 but I think upgrading first would be the best course of action. However, it's bedtime over here and I'll do the upgrade (clean install) in 24 hours tops. What do you think? Sorry about that and thanks again.

[JeremyB]

Mint 20 won't make any difference as you are already using the same kernel it has. Run this and post URL

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wget -N -t 5 -T 10 https://github.com/UbuntuForums/wireless-info/raw/master/wireless-info && chmod +x wireless-info && ./wireless-info && cat wireless-info.txt | nc termbin.com 9999

[FamCompKid]

[EDIT: I removed the URL because I'm not savvy enough to decide whether it's safe to publicly post my networking info. However, I'm keeping a text file in case someone needs it, although I doubt that.]

Thank you, that's great to hear!

[JeremyB]

Do

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sudo rm /etc/modprobe.d/8821cu.conf

Reboot and do

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./wireless-info && cat wireless-info.txt | nc termbin.com 9999

Post URL

[FamCompKid]

[EDIT: Removed the URL. Please see my previous reply.]

Thank you.

[JeremyB]

Lets try something from the github issue

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sudo modprobe -r 8821cu
sudo modprobe 8821cu rtw_RFE_type=0x26

See if it works

[FamCompKid]

IT'S WORKING THANK YOU SO MUCH!

Sorry I really have no clue but... I'll just have to do it all over again on LM 20? I'm upgrading any time this week.

Thank you again

[JeremyB]

Actually I would recommend doing

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echo "options 8821cu rtw_RFE_type=0x26" | sudo tee /etc/modprobe.d/8821cu.conf

That will load the module correctly at boot time rather than have to run those 2 commands each time