After installing Kubuntu 19.04, DNS stopped working after setting static IP address. Am able to successfully ping gateway address but name resolution does not work. Setting interface back to DHCP (automatic) and DNS starts working. Set interface back to static IP (manual) and DNS resolution stops. This suggests there might be a problem in the Network Manager configuration code. Where are the DNS server addresses stored nowadays? With Network Manager, Systemd, NetPlan etc. it's almost impossible to debug these types of problems. I've reviewed similar questions going back to 2006 but they don't pertain anymore as things have changed and their recommendations don't work anymore.
Static IP was set using Network Manager using the Edit Network Connections graphical dialog and yes, I set the nameserver addresses in the dialog. I assume, that once you click "apply" and "ok" those addresses get written somewhere. Question is, Where?