My campus lab has the Dell desktops. I am not sure the model, but the network devices are Broadcom BCM43228. As a result, after installation of the Ubuntu (they were not installed by me), Ubuntu cannot get WiFi connection to online.
Since my student mentioned that Windows can use the ethernet cable to share the wireless network, I asked him to help to share the wireless network from Windows on the other Dell desktop, and connect to the target Dell desktop.
This step works.
Next, I followed this Q and A post, just followed exactly all the commands there. Then reboot.
Yes! It works. Now, my students can test Ubuntu.