The offline notification is sent if the network connection between your system and our Server is lost for more than 15 min (15 min is a standard offline sending interval for the Pulseway Pro subscribers). As a Pulseway Pro subscriber, you can't change this setting, because it is a server-wide setting.

If you want to be able to configure this setting, you will need to consider the option to move to the Pulseway Team plan. With the Team subscription, you will receive your own instance, which you can configure.