Since Ubuntu 16.04 my internet connection did not work when it was managed by the "Network Manager".
When unmanaged the internet connection worked fine. Unmanaged = adding the wired connection to /etc/network/interfaces.
The passed few years I frequently searched the internet for a solution. I tried a lot, but nothing worked. Until today...
... somehow I always used an IP address starting with 169. I do not know exactly why it does not work in "Network Manager", but I do know that when I changed it to 192 - and let the "Network Manager" manage the connection - that I suddenly could ping 18.104.22.168.
When I tried to reach google.nl, it did not respond, but due to my internet search for a solution I knew I had to change /etc/resolve.conf and then it all worked!!!