I upgraded from 5.4 to 5.11 kernel version and now it works all, the WIFI, the Ethernet, the screen brightness and volume keys of the notebook. However I had to do one of the following things: disable the secure boot, or sign the kernel. I opted to do the first one first, then once with the system running I signed the new kernel and activated secure boot again.Also I came across this issue: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1859287
If you read through it you see that it was working and then someone else with Ubuntu 20.04 is having the same issues again. So it might be worth a try installing a newer kernel since according to the other source I linked says that the wifi should work with kernel 5.7 and above.
There are several GUI tools that allow you to install the mainline kernel on Ubuntu, the advantages of using one of these tools over doing it manually is that you will also get kernel updates once they are available.In my case, updating the kernel to 5.8.18 did the trick
An article that shows how to new kernel version- https://itsfoss.com/upgrade-linux-kernel-ubuntu/#install-manually