We are having issues sending downlink configuration data to our custom nrf9160 hardware from AWS-IoT Cloud.
The nrf9160 modem firmware version we are using is 1.3.4
The nrf9160 SDK version we are using is 1.7.0.
We are able to see the downlink data from within the AWS IoT mqtt console being executed from within AWS IoT mqtt console when we subscribe to a topic.
An example topic is: $aws/things/352656106334272/shadow/get/accepted/desired/cfg
What we notice is when we our hardware publish time is set to 120 seconds, we have 95 percent success rate in being able to send downlink configuration data to our hardware and change parameters. When the publish time is set to 900 seconds or larger which is our default publish time in most applications, our success rate is around 10 percent. It takes multiple tries before we are able to send the downlink configuration data.
Please advise on how we can debug this issue.