"No address associated with hostname" is a network error, it appears when a device has no Internet access.
If a device has no Internet access during a certain time, and you're using HTTP polling to deliver Push notifications, they are delivered when a device comes online. However you will see a warning "No address associated with hostname" in logs.
Note that HTTP polling delays the delivery of Push notifications by up to 15 minutes. I would recommend using MQTT instead (set the keep-alive time to 5 minutes or less to prevent connection break).