If your version of Linux does not support the Killer Wireless-1550 at install, and you are using Ubuntu 16.04 or later, or another version of Debian Linux, you can use this guide to Backport the drivers from the latest version of Ubuntu/Debian, enabling the Killer 1550 in 16.04 or later. We have confirmed that this will result in wireless connectivity in Ubuntu 16.04 with the Killer Wireless-AC 1550.
Please note that Secure Boot must be disabled in your BIOS before following these steps. If you are unsure how to disable Secure Boot, please refer to your machine or motherboard’s support materials or website.
Type or copy and paste the following commands in a terminal, one line at a time, pressing Enter after each command.
$ sudo apt-get install git
$ git clone https://git.kernel.org/pub/scm/linux/kernel/git/iwlwifi/backport-iwlwifi.git
$ cd backport-iwlwifi
$ make defconfig-iwlwifi-public
$ make -j4
$ sudo make install
Then restart.
Once you have done this, you should be able to connect to your wireless access point.
Credit goes to Jeremy31 on StackExchange for the guide – https://askubuntu.com/questions/1016903/alienware-17-r4-ubuntu-16-04-wifi-driver