My issue is communicating with these devices using the End Device Function set.
When I program any of them with the Coordinator or Router Function Set I am able to communicate with them both via the XBEE-API or the X-CTU with no issues. However when I attempt using the End Device Function set with any of them communication with the device becomes intermittent, even with X-CTU.
If you are able to read the parameters of the end device through X-CTU, then it may be the problem with the sleeping parameters of the end device i think.
You probably are not setting the ‘sleep’ parameters in the parents correctly. Yes, that seems odd, but you do need to set SN/SP in the Coordinator and Router correctly or your end-device appears to never talk because verytime it wakes, it has no ‘parent’.