RTL8822CE wireless adapter doesn't work on Ubuntu 18.04
The linux-firmware in Ubuntu 18.04 repository doesn't contain rtw8822c_wow_fw.bin file. In 20.04 it is already added.
You can get it this way. Run in a terminal:
sudo apt install git
git clone git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
sudo cp linux-firmware/rtw88/rtw8822c_wow_fw.bin /lib/firmware/rtw88
Reboot, and Wi-Fi should work.
You can delete the linux-firmware directory if you like. It is not needed after you install the firmware.