Congested network

My network consists of a coordinator node and 4 nodes with active end-device to sleep 200mSec and 4 end-device with idle sleep for 28 sec.

Every active node transmits about 1 time per second 4 bytes of data to the coordinator.
The problem is that sometimes some messages are lost or arriving very late (even 1 minute).
If increasing the number of active nodes (with sleep 200mSec of) the situation worsens considerably.

There may be some wrong configuration? Is there any trick to improve the situation?

I’m using XB24-BWIT-004 devices with firmware 2170 (coordinator) and firmware 2870 (end-device).

This seems to be a simple question about the reliability of the ZB firmware. Has nobody replied at all? Has anyone established that a small ZB network like this REALLY does work - or is this report considered unworthy of a reply from anyone with expertise in the ZB system?

You’ll need to backoff the frequency of your data transmission. You are likely overwhelming the network. Keep in mind that the sleep coordinator, which is also the coordinator in this case, can only hold one sleep message for all it’s sleeping nodes at a time.

Zigbee is best when used in a high latency and low data transmission frequency envionrment (once an hour to a day is common). By transmitting once a second on all nodes, you are introducing a lot of overhead.