Realtek 8811CU - Wifi adapter not working - (Mercusys MU6H)

Issues & Assistance Networking Support
1

Hello.
I've got usb wifi adapter Mercusys MU6H (on Realtek 8811CU) and can get it working on Garuda.
lsusb shows:
Bus 003 Device 005: ID 0bda:c811 Realtek Semiconductor Corp. 802.11ac NIC
and no specific driver
I found this driver AUR (en) - rtl8821cu-git
but don't know how to install it (complete newbie).
Thanx in advance for any assistance.

garuda-inxi

System:
Kernel: 5.16.4-zen1-1-zen x86_64 bits: 64 compiler: gcc v: 11.1.0
parameters: BOOT_IMAGE=/@/boot/vmlinuz-linux-zen
root=UUID=a4a07008-262c-4d06-a52e-7e21df95a3fc rw rootflags=subvol=@
quiet splash rd.udev.log_priority=3 vt.global_cursor_default=0 loglevel=3
Desktop: KDE Plasma 5.23.5 tk: Qt 5.15.2 info: latte-dock wm: kwin_x11
vt: 1 dm: SDDM Distro: Garuda Linux base: Arch Linux
Machine:
Type: Desktop System: Gigabyte product: Z87X-UD3H v: N/A
serial: <superuser required> Chassis: type: 3 serial: <superuser required>
Mobo: Gigabyte model: Z87X-UD3H-CF v: x.x serial: <superuser required>
BIOS: American Megatrends v: F9 date: 03/18/2014
Battery:
Device-1: apple_mfi_fastcharge model: N/A serial: N/A charge: N/A
status: N/A
Device-2: hidpp_battery_0 model: Logitech Wireless Keyboard K360
serial: <filter> charge: 100% (should be ignored) rechargeable: yes
status: Discharging
CPU:
Info: model: Intel Core i5-4670K bits: 64 type: MCP arch: Haswell family: 6
model-id: 0x3C (60) stepping: 3 microcode: 0x28
Topology: cpus: 1x cores: 4 smt: <unsupported> cache: L1: 256 KiB
desc: d-4x32 KiB; i-4x32 KiB L2: 1024 KiB desc: 4x256 KiB L3: 6 MiB
desc: 1x6 MiB
Speed (MHz): avg: 2516 high: 3294 min/max: 800/3800 scaling:
driver: intel_cpufreq governor: schedutil cores: 1: 2399 2: 2622 3: 3294
4: 1750 bogomips: 27136
Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Vulnerabilities:
Type: itlb_multihit status: KVM: VMX disabled
Type: l1tf
mitigation: PTE Inversion; VMX: conditional cache flushes, SMT disabled
Type: mds mitigation: Clear CPU buffers; SMT disabled
Type: meltdown mitigation: PTI
Type: spec_store_bypass
mitigation: Speculative Store Bypass disabled via prctl
Type: spectre_v1
mitigation: usercopy/swapgs barriers and __user pointer sanitization
Type: spectre_v2 mitigation: Full generic retpoline, IBPB: conditional,
IBRS_FW, STIBP: disabled, RSB filling
Type: srbds mitigation: Microcode
Type: tsx_async_abort status: Not affected
Graphics:
Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics
vendor: Gigabyte driver: i915 v: kernel bus-ID: 00:02.0 chip-ID: 8086:0412
class-ID: 0300
Device-2: NVIDIA GK104 [GeForce GTX 770] vendor: Gigabyte driver: nouveau
v: kernel bus-ID: 01:00.0 chip-ID: 10de:1184 class-ID: 0300
Device-3: Logitech HD Pro Webcam C920 type: USB
driver: snd-usb-audio,uvcvideo bus-ID: 3-10.4:8 chip-ID: 046d:082d
class-ID: 0102 serial: <filter>
Display: x11 server: X.Org 1.21.1.3 compositor: kwin_x11 driver:
loaded: intel,nouveau unloaded: modesetting alternate: fbdev,nv,vesa
display-ID: :0 screens: 1
Screen-1: 0 s-res: 2560x1080 s-dpi: 96 s-size: 677x285mm (26.7x11.2")
s-diag: 735mm (28.9")
Monitor-1: HDMI-4 res: 2560x1080 hz: 60 dpi: 81
size: 798x334mm (31.4x13.1") diag: 865mm (34.1")
Message: Unable to show advanced data. Required tool glxinfo missing.
Audio:
Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor HD Audio
driver: snd_hda_intel v: kernel bus-ID: 00:03.0 chip-ID: 8086:0c0c
class-ID: 0403
Device-2: Intel 8 Series/C220 Series High Definition Audio
vendor: Gigabyte driver: snd_hda_intel v: kernel bus-ID: 00:1b.0
chip-ID: 8086:8c20 class-ID: 0403
Device-3: NVIDIA GK104 HDMI Audio vendor: Gigabyte driver: snd_hda_intel
v: kernel bus-ID: 01:00.1 chip-ID: 10de:0e0a class-ID: 0403
Device-4: Logitech HD Pro Webcam C920 type: USB
driver: snd-usb-audio,uvcvideo bus-ID: 3-10.4:8 chip-ID: 046d:082d
class-ID: 0102 serial: <filter>
Sound Server-1: ALSA v: k5.16.4-zen1-1-zen running: yes
Sound Server-2: PulseAudio v: 15.0 running: no
Sound Server-3: PipeWire v: 0.3.44 running: yes
Network:
Device-1: Intel Ethernet I217-V vendor: Gigabyte driver: e1000e v: kernel
port: f080 bus-ID: 00:19.0 chip-ID: 8086:153b class-ID: 0200
IF: eno1 state: down mac: <filter>
Device-2: Realtek 802.11ac NIC type: USB driver: N/A bus-ID: 3-9.2:5
chip-ID: 0bda:c811 class-ID: 0000 serial: <filter>
IF-ID-1: enp0s20u9u1c4i2 state: up speed: N/A duplex: N/A mac: <filter>
Bluetooth:
Device-1: Broadcom BCM20702A0 Bluetooth 4.0 type: USB driver: btusb v: 0.8
bus-ID: 3-4:2 chip-ID: 0a5c:21e8 class-ID: fe01 serial: <filter>
Report: bt-adapter ID: hci0 rfk-id: 0 state: up address: <filter>
Drives:
Local Storage: total: 2.95 TiB used: 7.12 GiB (0.2%)
SMART Message: Unable to run smartctl. Root privileges required.
ID-1: /dev/sda maj-min: 8:0 vendor: SanDisk model: SDSSDX120GG25
size: 111.79 GiB block-size: physical: 512 B logical: 512 B speed: 6.0 Gb/s
type: SSD serial: <filter> rev: R201 scheme: MBR
ID-2: /dev/sdb maj-min: 8:16 vendor: Plextor model: PX-128M5S
size: 119.24 GiB block-size: physical: 512 B logical: 512 B speed: 6.0 Gb/s
type: SSD serial: <filter> rev: 1.05 scheme: MBR
ID-3: /dev/sdc maj-min: 8:32 vendor: Western Digital
model: WD10EZRZ-00HTKB0 size: 931.51 GiB block-size: physical: 4096 B
logical: 512 B speed: 6.0 Gb/s type: HDD rpm: 5400 serial: <filter>
rev: 1A01 scheme: MBR
ID-4: /dev/sdd maj-min: 8:48 vendor: Western Digital
model: WD10EZRZ-00HTKB0 size: 931.51 GiB block-size: physical: 4096 B
logical: 512 B speed: 6.0 Gb/s type: HDD rpm: 5400 serial: <filter>
rev: 1A01 scheme: MBR
ID-5: /dev/sde maj-min: 8:64 vendor: Western Digital
model: WD10EZRZ-00HTKB0 size: 931.51 GiB block-size: physical: 4096 B
logical: 512 B speed: 6.0 Gb/s type: HDD rpm: 5400 serial: <filter>
rev: 1A01 scheme: MBR
Partition:
ID-1: / raw-size: 119.24 GiB size: 119.24 GiB (100.00%)
used: 7.12 GiB (6.0%) fs: btrfs dev: /dev/sdb1 maj-min: 8:17
ID-2: /home raw-size: 119.24 GiB size: 119.24 GiB (100.00%)
used: 7.12 GiB (6.0%) fs: btrfs dev: /dev/sdb1 maj-min: 8:17
ID-3: /var/log raw-size: 119.24 GiB size: 119.24 GiB (100.00%)
used: 7.12 GiB (6.0%) fs: btrfs dev: /dev/sdb1 maj-min: 8:17
ID-4: /var/tmp raw-size: 119.24 GiB size: 119.24 GiB (100.00%)
used: 7.12 GiB (6.0%) fs: btrfs dev: /dev/sdb1 maj-min: 8:17
Swap:
Kernel: swappiness: 133 (default 60) cache-pressure: 100 (default)
ID-1: swap-1 type: zram size: 15.51 GiB used: 0 KiB (0.0%) priority: 100
dev: /dev/zram0
Sensors:
System Temperatures: cpu: 29.8 C mobo: 27.8 C gpu: nouveau temp: 43.0 C
Fan Speeds (RPM): N/A gpu: nouveau fan: 1020
Info:
Processes: 217 Uptime: 33m wakeups: 58 Memory: 15.52 GiB
used: 2.32 GiB (14.9%) Init: systemd v: 250 tool: systemctl Compilers:
gcc: 11.1.0 clang: 13.0.0 Packages: pacman: 1144 lib: 294 Shell: fish
v: 3.3.1 default: Bash v: 5.1.16 running-in: konsole inxi: 3.3.12
Garuda (2.5.3-1):
System install date:     2022-02-23
Last full system update: 2022-02-23
Is partially upgraded:   Yes
Relevant software:       NetworkManager
Windows dual boot:       <superuser required>
Snapshots:               Snapper
Failed units:

Before you open a new help request, read relevant sections of the Arch and Garuda wiki.
Thoroughly search your issue and any error messages in the forum and on the web.

Report everything you have already attempted to solve your problem.

2

Hi there, welcome.
You can install it opening a terminal and entering:

paru rtl8821cu-git

You'll be presented a "PKGBUILD" to review.
Exit from the review pressing button Q and confirm the installation with Y.
Careful, a comment in the AUR says "Every time I get a kernel update, I have to re-install this via AUR using my smartphone". Smarter packages are built with DKMS and in this way this problem would not occur.
I see a package rtl8821cu-dkms-git do exist, but I don't kwon if it works well for your RTL8811CU. Maybe it's worth trying.

3 Likes
3

I would very much recommend the use of the DKMS driver package instead: ~~https://aur.archlinux.org/packages/rtl8821cu-dkms-git~~ not this one, the one tbg linked below which is more up-to-date.

That way it will automatically rebuild every time you update the kernel.

3 Likes
4

I would recommend installing the rtl8821cu-morrownr-dkms-git driver from the AUR:

http://aur.archlinux.org/packages/rtl8821cu-morrownr-dkms-git

Uninstall any others you've installed before you install the rtl8821cu-morrownr-dkms-git driver.

To install:

paru rtl8821cu-morrownr-dkms-git

You will likely need to build this driver on the linux-lts kernel to get it to work.

4 Likes
5

I can't git clone http://aur.archlinux.org/packages/rtl8821cu-morrownr-dkms-git
It says fatal: repository not found (

6

Try using paru or yay to install the driver:

paru rtl8821cu-morrownr-dkms-git
2 Likes
7

That’s because you used the wrong URL. Look at the package page and see the difference between the web page URL and the git repo URL.

10

Hi there Vlad.

I see you were online yesterday, but you have not responded to those attempting to help you since your initial request for help.

Were you successful in getting the rtl8821cu-morrownr-dkms-git driver to install for you?

If you could not get it working, be sure to install and then boot into the linux-lts kernel before building the driver. The driver will not likely work on the newest kernels, so you must use the LTS kernel until the driver is updated to properly support the newest kernel versions.

I would be happy to provide further assistance if you are still having problems, but you must also participate in the troubleshooting process to make headway with this matter.

If your issue has been successfully resolved, please be kind enough to mark your thread as solved and give the steps required to solve your issue.

Your cooperation in keeping the forum neat and tidy by not leaving threads dangling would be greatly appreciated.

Edit:

Also be sure to disable MAC address randomization if you are experiencing connectivity issues with this driver.

1 Like
11

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