To my benefit or downfall, whichever way you look at it, I bought the Comfast CF-915AC USB Wifi Adapter from Amazon. This proved to be super difficult to install. Me being a noob in Wifi networking in Linux. After 3 part time days of fiddling with it, it is now work. Here’s my steps and how I got it working.

Firstly, the USB Wifi Adapter came with a CD Rom to install the driver. I don’t have a CD Rom drive, so I hit Google, and started looking for what driver to use and how to install.

Under the COMFAST Wiki it’s listed as using the RTL8811AU Realtek chipset.

I tried looking for RTL8811AU drivers via Google, since the product only came with a disk for installation and couldn’t find any drivers that matched. The Comfast official driver download links returned 404 page not found errors in Chinese!

I then found this Ubuntu formus blog and it said that the RTL8812AU driver could be used.

I then followed this StackExchange answer to get the USB driver RTL8812AU correctly installed:

https://askubuntu.com/a/1045927/324695

Using ifconfig, the interface was present, but it didn’t have an IP address.

I am using netplan and my /etc/netplan/01-netcfg.yml currently looks like this:

network:
  version: 2
  renderer: networkd
  ethernets:
    enp6s0:
      dhcp4: true
      nameservers:
        addresses: [8.8.8.8,8.8.4.4]
  wifis:
    wlx40a5ef40734c:
      dhcp4: true
      nameservers:
        addresses: [192.168.0.1, 8.8.8.8]
      access-points:
        "my-wifi-router-name":
          password: "my-password"

This is becasue I have WPA security enabled, so the netplan yaml wasn’t work.

I then followed this StackExchange answer:

https://askubuntu.com/a/16588/324695

Using the wpasupplicant package, I generated a wpa.conf file as suggested, and using these commands could connect to the Wifi Router

# install package
sudo apt install wpa_supplicant

# generates a file
wpa_passphrase SSID PASSWORD > wpa.conf

# command uses the file to connect, and runs as a daemon
sudo wpa_supplicant -i wlx40a5ef40734c -c wpa.conf -D wext -B

Everything is now working. After a reboot, the Wifi still connects. I am smiling!

Steps only

Here are the commands / steps only extracted from the above blogs.

Install driver

First remove any old drivers in /usr/src

Then, install new driver:

sudo apt purge rtl8812au-dkms
sudo apt install git
git clone https://github.com/abperiasamy/rtl8812AU_8821AU_linux.git
cd rtl8812AU_8821AU_linux
sudo make -f Makefile.dkms install
sudo modprobe rtl8812au

Can view that driver is covered:

modinfo rtl8812au | grep A811

Run ifconfig -a and the Wifi interface should be up.

Configure netplan

Configure netplan yaml file, /etc/netplan/01-netcfg.yml as shown above

Run sudo netplan apply to apply changes.

wpasupplicant

Install this package for WPA security support

sudo apt install wpasupplicant

Reboot and check

Reboot computer and check

reboot

# should show the wifi interface now with an IP address if working
ifconfig -a

Logging in remotely

There are 3 steps to do this

1. Assign a static IP address to your home network

This can be done from logging into your Wifi router. The URL to login will be on the bottom of your Wifi router.

I have a Netgear router, so I

2. The DL machine should be DHCP registered to an IP address

For me, this was already done in the previous step using netplan

3. Add port forwarding

This is configurable when logged in to the Router config. For me, this Netgear guide helped me setup port forwarding.

4. Test

I tested by connecting to my phone Wifi hotspot with my laptop then tested that I could ssh to the DL machine

ssh -i ~/.ssh/my.pem username@hostname

Some interesting points

ifconfig

ifconfig will show internet interfaces that are up

ifconfig -a will show all internet interfaces whether they are up or down

ifconfig was showing the Wifi interface as up, but with no IP. This meant that the USB Wifi adapter driver (driver) installation worked and it was registered as an interface in netplan but couldn’t connect to the network. It was the WPA security blocking it at this point.

lshw

lshw -C network will show hardware. -C network to only show “network” class of hardware.

After successfully installing the driver, I could see the wifi network as DISABLED. Then running netplan apply this show the network as enabled.

Commands used

# list usb ports and connected devices
lsusb

# configure network interfaces
ifconfig

# configure wifi network interfaces
iwconfig

# get detailed wifi info
iwlist <interface> s

# dynamic kernal support module
dkms

# ip show an manipulate routing, network devices, interfaces
ip link set <interface> up/down

# list hardware
lshw -C network


netplan apply

netplan --debug generate

# check if there's internet
ping -c3 www.ubuntu.com