GNU/Linux Ubuntu 18.04 Realtek rtl8723ae Driver Installation Guide
Hi! The linked Tutorial shows you Step-by-Step How to Install Realtek rtl8723ae Wireless Driver for Ubuntu 18.04 Bionic LTS GNU/Linux.
And the Realtek rtl8723ae Ubuntu 18.04 Driver Installation is Quick & Easy, involving at most the execution of some Basic Shell Commands.
Finally, if you have Different Card then See this Other Guide: How to Install Realtek Wifi Drivers on Ubuntu.
Installing Realtek rtl8723ae Driver for Ubuntu