Cellular IoT devices cannot stay connected to AWS

Question

Cellular IoT devices keep reconnecting to AWS. The cellular provider indicates that the problem is not the cellular network because their logs show the devices connected for upwards of 16 hours at a time. When the devices are at other locations, they stay connected for several hours. Even at the trial site, the first device stayed up for over an hour. All subsequent devices stayed up less than ten minutes. MQTT Keep Alive is 1200 seconds. We have an application level keep alive of 10 minutes. Exported Iot Console logs available. Working on Cloudwatch logs

Answer

Reconnections, or TCP session timeouts, via mobile network operators (MNOs) can be challenging. Most use some for of carrier grade NAT that will manage connections from the mobile device to the public Internet. You can get a better indication of which side (client or IoT server) disconnected from the CloudWatch logs.

One thing to test is to reduce the device's MQTT keepalive to a lower value and monitor. While each MNO is different, and can be different depending where the are deployed, I would start with a value of 270-290 seconds, which is just under 5 minutes--a common value seen for expiring inactive TCP sessions.

Cellular IoT devices cannot stay connected to AWS

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