Just a quick note that 19.04 Ubuntu reached EOL on Jan 23rd, 2020. Ubuntu has several releases that support 4.18+ kernels [0]. I recommend using 19.10, but you can also use a more recent HWE kernel for the 18.04 LTS [1].
[0] https://ubuntu.com/about/release-cycle
[1] https://wiki.ubuntu.com/Kernel/LTSEnablementStack