HASSIO - ADDONS & UPDATE to new version failing - registry-1.docker.io - authentication required?

I am running Hassio on Ubuntu and after activating nabu casa (might be a coincidence) I can no longer install/update addons and upgrade Home Assistance … I find the following errors in my log:

update addon:

19-10-01 19:39:23 INFO (SyncWorker_9) [hassio.docker.interface] Update image homeassistant/amd64-addon-check_config:3.0 to homeassistant/amd64-addon-check_config:3.1
19-10-01 19:39:23 INFO (SyncWorker_9) [hassio.docker.interface] Pull image homeassistant/amd64-addon-check_config tag 3.1.
19-10-01 19:39:23 ERROR (SyncWorker_9) [hassio.docker.interface] Can't install homeassistant/amd64-addon-check_config:3.1 -> 500 Server Error: Internal Server Error ("Get https://registry-1.docker.io/v2/: dial tcp: lookup registry-1.docker.io on [::1]:53: read udp [::1]:45654->[::1]:53: read: connection refused").

upgrade HA

19-10-01 19:43:41 INFO (MainThread) [hassio.homeassistant] Update Home Assistant to version 0.99.3
19-10-01 19:43:41 INFO (SyncWorker_18) [hassio.docker.interface] Update image homeassistant/qemux86-64-homeassistant:0.98.5 to homeassistant/qemux86-64-homeassistant:0.99.3
19-10-01 19:43:41 INFO (SyncWorker_18) [hassio.docker.interface] Pull image homeassistant/qemux86-64-homeassistant tag 0.99.3.
19-10-01 19:43:41 ERROR (SyncWorker_18) [hassio.docker.interface] Can't install homeassistant/qemux86-64-homeassistant:0.99.3 -> 500 Server Error: Internal Server Error ("Get https://registry-1.docker.io/v2/: dial tcp: lookup registry-1.docker.io on [::1]:53: read udp [::1]:36345->[::1]:53: read: connection refused").
19-10-01 19:43:41 WARNING (MainThread) [hassio.homeassistant] Update Home Assistant image fails

Can someone help to interprete this ? what connection is here refused ?
When I try to access: https://registry-1.docker.io/v2/ in a browser

{"errors":[{"code":"UNAUTHORIZED","message":"authentication required","detail":null}]}

What authentication is this ? This must be build in in HA ?

Chris