Wait, you're contracting yourself.
when they goes to sleep and sending only heartbeat
Nothing there when in sleep mode, like device not communicating at all.
Im trying to figure out what happened, those devices goes at sleep mode as manufacturer tolds me and sends only heartbeat.
but heartbeat seems not recognized from traccar like the first post said so the device goes offline
What do you mean not recognized? Where's the log with those heartbeats? Where's the proof that your device sends it?
The device its communicate and always online at other platform, not traccar as i test them. So the device it communicates, via heartbeat or something else which not recognized from traccar.
This i understand, maybe im wrong idk.
You're wrong. If device sends something, you will see it in the logs.
And then after offline, the issue this happened :
https://www.traccar.org/forums/topic/cantrack-tk100-onlineoffline-and-unknown-status/