We had a corrupt duckieshell and had to reinstall Umbunto on our laptop. When setting up our laptop we were able to ping the duckiebot. Then when we try to ssh into the duckie were revive the following message. “Could not resolve hostname ourhostname: Name or service not known. We have tried to use ssh username.local and the same message appears. It does not accept the previously established password.
These problems are pretty difficult to debug. First – by Umbunto you mean “Ubuntu” correct? You should not have needed to reinstall Ubuntu due to a corrupt duckieshell. You can wipe away the local folder (usually ~/.dt-shell) and reinstall.
One way or another – it is not able to find the IP of your robot. To confirm this you could type:
$ nslookup [hostname]
One other worry from your question is that you write “ssh username.local” but it should be “ssh hostname.local”. As you can see here unless you changed the hostname, it should be “duckiebot” so make sure you are using the correct hostname.