So other ppl don’t lose 1day figuring this one out.
The way to connect this add-on GitHub - fredrikbaberg/hassio-addons: Intended home for hassio addons, if time allows.
from CURA octoprint is NOT to go to the link you get on the UI when you open the addon UI.
like https://servername/774437fd_octoprint/dashboard
But you have to enable the 5000 port on the addon
and then either reverse proxy to that port or just use the plain old IP to connect to it.