I recommend that we solve the Elastic Endpoint connection issue in Endpoint 7.9 "Degraded and dashboards" and get your Endpoints in a good state. Once you are able to see Detection alerts coming from your Elastic Endpoints, you can add exceptions directly from the Detection Alerts page as well https://www.elastic.co/guide/en/security/current/alerts-ui-manage.html#add-exception-from-alerts.