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I've buyed a Wifi Adapter but there isn't the driver for Linux. I have installaed the driver on Windows and read the code 8811CU. I followed too much guide but it never work, this is the most detailed:

After have followed this the WiFi adapter don't work, there isn't the wlan interface and the led is OFF.

Here some output:

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

root@user-PC-Desktop:/usr/src/rtl8821CU# lsusb
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 005: ID 0bda:1a2b Realtek Semiconductor Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 003: ID 04b3:3025 IBM Corp. NetVista Full Width Keyboard
Bus 003 Device 002: ID 046d:c077 Logitech, Inc. M105 Optical Mouse
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

after:

root@user-PC-Desktop:/usr/src/rtl8821CU# lsusb
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 006: ID 0bda:c811 Realtek Semiconductor Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 003: ID 04b3:3025 IBM Corp. NetVista Full Width Keyboard
Bus 003 Device 002: ID 046d:c077 Logitech, Inc. M105 Optical Mouse
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub



root@user-PC-Desktop:~# sudo lshw 
          description: USB controller
          product: MCP78S [GeForce 8200] EHCI USB 2.0 Controller
          vendor: NVIDIA Corporation
          physical id: 2.1
          bus info: pci@0000:00:02.1
          version: a1
          width: 32 bits
          clock: 66MHz
          capabilities: debug pm ehci bus_master cap_list
          configuration: driver=ehci-pci latency=0 maxlatency=1 mingnt=3
          resources: irq:22 memory:fde7ec00-fde7ecff
        *-usbhost
             product: EHCI Host Controller
             vendor: Linux 5.3.0-45-generic ehci_hcd
             physical id: 1
             bus info: usb@1
             logical name: usb1
             version: 5.03
             capabilities: usb-2.00
             configuration: driver=hub slots=6 speed=480Mbit/s
           *-usb UNCLAIMED
                description: Generic USB device
                product: 802.11ac NIC
                vendor: Realtek
                physical id: 6
                bus info: usb@1:6
                version: 2.00
                serial: 123456
                capabilities: usb-2.00
                configuration: maxpower=500mA speed=480Mbit/s


root@user-PC-Desktop:~# sudo lshw -c network
  *-network                 
       description: Ethernet interface
       product: MCP77 Ethernet
       vendor: NVIDIA Corporation
       physical id: a
       bus info: pci@0000:00:0a.0
       logical name: enp0s10
       version: a2
       serial: 00:21:97:ec:24:25
       size: 100Mbit/s
       capacity: 100Mbit/s
       width: 32 bits
       clock: 66MHz
       capabilities: pm msi ht bus_master cap_list ethernet physical mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=forcedeth driverversion=0.64 duplex=full ip=192.168.1.115 latency=0 link=yes maxlatency=20 mingnt=1 multicast=yes port=MII speed=100Mbit/s
       resources: irq:30 memory:fde7c000-fde7cfff ioport:c880(size=8) memory:fde7e400-fde7e4ff memory:fde7e000-fde7e00f

root@user-PC-Desktop:~# lspci -nnk | grep -iA2 net
00:0a.0 Ethernet controller [0200]: NVIDIA Corporation MCP77 Ethernet [10de:0760] (rev a2)
    Subsystem: Elitegroup Computer Systems MCP77 Ethernet [1019:1b67]
    Kernel driver in use: forcedeth
    Kernel modules: forcedeth

root@user-PC-Desktop:~# lsmod
Module                  Size  Used by
nls_iso8859_1          16384  1
snd_hda_codec_via      20480  1
snd_hda_codec_generic    81920  1 snd_hda_codec_via
ledtrig_audio          16384  1 snd_hda_codec_generic
snd_hda_codec_hdmi     57344  1
snd_hda_intel          53248  4
snd_seq_midi           20480  0
snd_seq_midi_event     16384  1 snd_seq_midi
edac_mce_amd           32768  0
snd_intel_nhlt         20480  1 snd_hda_intel
snd_hda_codec         131072  4 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec_via
snd_hda_core           90112  5 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,snd_hda_codec_via
serio_raw              20480  0
input_leds             16384  0
snd_rawmidi            36864  1 snd_seq_midi
snd_hwdep              20480  1 snd_hda_codec
snd_seq                69632  2 snd_seq_midi,snd_seq_midi_event
k8temp                 16384  0
snd_pcm               102400  4 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,snd_hda_core
wmi_bmof               16384  0
snd_seq_device         16384  3 snd_seq,snd_seq_midi,snd_rawmidi
snd_timer              36864  2 snd_seq,snd_pcm
snd                    86016  19 snd_hda_codec_generic,snd_seq,snd_seq_device,snd_hda_codec_hdmi,snd_hwdep,snd_hda_intel,snd_hda_codec,snd_timer,snd_hda_codec_via,snd_pcm,snd_rawmidi
soundcore              16384  1 snd
mac_hid                16384  0
sch_fq_codel           20480  2
parport_pc             40960  1
ppdev                  24576  0
lp                     20480  0
parport                53248  3 parport_pc,lp,ppdev
ip_tables              32768  0
x_tables               40960  1 ip_tables
autofs4                45056  2
uas                    24576  0
usb_storage            73728  2 uas
hid_generic            16384  0
usbhid                 53248  0
hid                   126976  2 usbhid,hid_generic
radeon               1454080  11
i2c_algo_bit           16384  1 radeon
ttm                   102400  1 radeon
drm_kms_helper        180224  1 radeon
syscopyarea            16384  1 drm_kms_helper
sysfillrect            16384  1 drm_kms_helper
sysimgblt              16384  1 drm_kms_helper
psmouse               151552  0
fb_sys_fops            16384  1 drm_kms_helper
drm                   491520  6 drm_kms_helper,radeon,ttm
ahci                   40960  0
pata_acpi              16384  0
forcedeth              73728  0
libahci                32768  1 ahci
pata_amd               20480  1
i2c_nforce2            20480  0
video                  49152  0
floppy                 81920  0
wmi                    32768  1 wmi_bmof



root@user-PC-Desktop:~# ls /lib/modules/$(uname -r)/kernel/drivers/net/wireless/realtek/rtl8821cu
8821cu.ko

root@user-PC-Desktop:~# sudo dkms status
bcmwl, 6.30.223.271+bdcom, 5.3.0-45-generic, x86_64: installed
rtl8821CU, 5.4.1, 5.3.0-45-generic, x86_64: installed (WARNING! Diff between built and installed module!)

root@user-PC-Desktop:~# sudo rfkill list all
root@user-PC-Desktop:~# iwconfig 
lo        no wireless extensions.

enp0s10   no wireless extensions.

Can someone help me to solve this problem???

7
  • Please edit your question to show the result of the terminal command: sudo modprobe 8821cu && dmesg | grep -e 8821 -e rtl Welcome to Ask Ubuntu.
    – chili555
    Apr 5, 2020 at 21:52
  • 1
    sudo modprobe 8821cu && dmesg | grep -e 8821 -e rtl [ 458.974961] 8821cu: loading out-of-tree module taints kernel. [ 458.982707] 8821cu: module verification failed: signature and/or required key missing - tainting kernel [ 458.999712] RTW: rtl8821cu v5.4.1_28754.20180921_COEX20180712-3232 [ 458.999714] RTW: rtl8821cu BT-Coex version = COEX20180712-3232 [ 459.418484] RTW: ERROR rtl8821c_fw_dl Download Firmware from array failed [ 459.594201] usbcore: registered new interface driver rtl8821cu [ 472.877210] RTW: ERROR rtl8821c_fw_dl Download Firmware from array failed
    – fbaldini93
    Apr 6, 2020 at 5:57
  • @chili555 can you help me?
    – fbaldini93
    Apr 6, 2020 at 19:25
  • I have no suggestions as to how to fix the current driver. I can only suggest that you try a newer version: github.com/brektrou/rtl8821CU/issues/30 Please post back if you need a step-by-step.
    – chili555
    Apr 6, 2020 at 20:16
  • I have to uninstall the previous version?
    – fbaldini93
    Apr 6, 2020 at 21:07

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