GNU/Linux Mint 19 ASUS USB-AC56 Wifi Driver Setup – Step-by-step Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install ASUS USB-AC56 AC1300 Wireless 802.11ac Driver in Mint 19.x Tara/Tessa/Tina/Tricia LTS GNU/Linux Desktop.
And the Mint 19 ASUS USB-AC56 Setup is based on the Realtek rtl8812BU Chipset Driver Installation.
So the linked guide explain How to Download and Install the rtl8812BU Linux Driver.
Finally, in case to check your Adapter Chipset see: How to Check Wireless Device ID on GNU/Linux.
GNU/Linux Mint 19 ASUS USB-AC56 Wireless Driver Installation Guide
On the Driver Download page, take into account that the Morrownr release is currently the recommended choice for this Dongle.