After installing an image of the Ubuntu server on the Raspberry 4, the wifi is not automatically configured after the initial book.

In order to be able to use the WiFi follow the steps described below for setting up your wifi in your SD card, and then reboot your raspberry (make sure that the indentation in the yaml file is correct, and also your WiFi access point is enclosed in quotes):

https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#3-wifi-or-ethernet