Turn on the push notifications in the message centre of the Apple device. 

The firewall of the modem prevents a connection with APNS (Apple Push Notification Server). 

Open the listening ports on the router, see the Apple support site.

 https://support.apple.com/en-us/HT203609 

If you have any additional questions about your IVM-180, you can always contact us via this website. 

Please state the question or complaint clearly so we can serve you well.