@stefan-de-lange Hi Stefan,
Thanks for your reply,
What protocol are you using?
We are using UDP over NB-IoT.
I would definitely not recommend to register every hour
I agree. However, the customer can configure how often the device sends data to our backend. The connection interval can be set between 1 and 24 hours. In the case of 8+ hours which most of our customers configure, it is for our device more power efficient to shut everything down than go to PSM. In my original post, I mentioned 1 hour, but the same problem occurs when configuring a connection interval of more than 1 hour.
about the message queue
I am aware that the messages are queued. Waiting at least 3 minutes to send a reply will mean the connection of the nb-IoT device is already closed. This is the intended behavior for our situation. Next time the device comes online, it should receive the message from the queue. The problem is, it doesn’t receive any of the messages most of the time.
My guess is that when the modem deregisters itself from the network, the downlink message queue is cleared. But again t-mobile has to confirm this…
Would be really nice if T-mobile could confirm this.
We saw that if we don’t deregister from the network but just pull the battery out and after an hour replugs it again, the device enters its init loop and registers at the network and does receive all messages. But this is of course not a solution.
Can you please try again without shutting down but staying in PSM mode?
For testing purposes, I can try to implement this. However, this is not our desired solution.