As of AppDaemon 4.5, this is no longer true. If anyone stumbles across this thread receiving the error message As of AppDaemon 4.5 the host name specified in the URL must resolve to a known host while using this template and AppDaemon does not start, please expand the More Settings option in the template, and change the DASH_URL variable to http://0.0.0.0:5050 or your preferred port. Editing the AppDaemon.yaml file will not work and this template will overwrite the url on restart. Took me two hours to find this. Hope I can help someone else.