I was also working on getting netmaker client to work on Ubuntu Core. It mainly runs on snapd daemon service instead of systemd. When in try creating the netmaker client. I get a message: "rpc error: code = Unknown desc = Key: 'Node.MacAddress' Error:Field validation for 'MacAddress' failed on the 'macaddress_unique' tag" I am not able to debug why this is happening. DO you know why this happens? After this message appears, i am unable to add this system as a node.