AC600M USB WiFi Adapter

Having gotten frustrated with the X1C7 WiFi issue, I decided to use an external USB WiFi adapter. Here is the specific adapter1 I purchased from Amazon. It does not work with Linux out of the box; however, the shipment came with a mini CD (with presumably the Windows driver) that had the code RTL8811/RTL8812 which hinted at the possible Linux driver to use.

Initial investigation

After inserting the adapter to USB port, dmesg displayed

[  +0.933146] usb 1-3: USB disconnect, device number 6
[  +4.194956] usb 1-3: new high-speed USB device number 11 using xhci_hcd
[  +0.126132] usb 1-3: New USB device found, idVendor=0bda, idProduct=c811, bcdDevice= 2.00
[  +0.000006] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  +0.000003] usb 1-3: Product: 802.11ac NIC
[  +0.000003] usb 1-3: Manufacturer: Realtek
[  +0.000003] usb 1-3: SerialNumber: 123456

And lsusb identified (why?) the device ID c811:

$ lsusb | grep 802
Bus 001 Device 011: ID 0bda:c811 Realtek Semiconductor Corp. 802.11ac NIC

Which led me to this post that indicated that I needed to use the 8821cu (matching what’s on the mini CD) Linux driver for this particular hardware.

Configuring NixOS

Fortunately, this is all in nixpkgs; I only had to add the following to my NixOS configuration and reboot:

boot.extraModulePackages = [ config.boot.kernelPackages.rtl8821cu ];

Reboot.

Using the card

Expect to see the card in ifconfig. If connecting via nmtui produces this error:

Could not activate connection
Insufficient privileges

… use sudo nmtui.

  1. Product title: WiFi Adapter Flenco 600Mbps WiFi Dongle Mini Dual Band 2.4G/5G USB Wireless Network Adapter Support for Win 7/8/8.1/10/XP/Vista

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