I have read the reference (Intel wifi Support for AX200 (Cyclone Peak)), but I still have problems about this issue.
I tried to manually update to 5.1, but somehow it creates more problems, so I reinstalled ubuntu 16.04 again. I followed the instruction from https://www.youtube.com/watch?v=lKqZ1sv0DVc, but it only updates to kernel 4.15.0-65 and says it's the newest version:
$ sudo apt-get install --install-recommends linux-generic-hwe-16.04
(optional to add xserver-xorg-hwe-16.04)
Reboot and check your system works ok
$ sudo apt-get autoremove
$ sudo apt-get purge linux-generic linux-headers-generic linux-image-generic
Besides, in Linux* Support for Intel® Wireless Adapters website (https://www.intel.com/content/www/us/en/support/articles/000005511/network-and-i-o/wireless-networking.html). Should I still download the firmware of Intel® Wi-Fi 6 AX200 160MHz, even though it says the kernel need 5.1+?
Can somebody provide code guidance? thanks very much!