No network devices available - Ubuntu 16.04 (No wifi/no Ethernet)

I found the solution here, post#4. Please, keep in mind that in /etc/NetworkManager/NetworkManager.conf you should have managed=true.

I was having this problem for a long time. I was using an older kernel version as a workaround, but the kernel version I was using started having the same issue.

I have the r8168 driver (you can check that out by running dkms status on a terminal), and the solution for me was to download the driver on the realtek website, extract the folder, and run the autorun.sh script (by running sudo <extracted_folder_path>/autorun.sh on a terminal).