How does a sleeping end device retain network information in order to send input change immediatly ?

I am using serie 2 xbee modules in API mode.
I have a coordinator, a router and 4 end devices.
End devices are configured to wake up on pin 9 de-asserting.
Out of my end devices, only one of them wakes up, sends its message immediatly and goes back to sleep. This is the behaviour I would like to get for each radio.

The others need continuous inputs to keep the radio awake so that it can find the coordinator or router and finally send the message.

If it is helping I am using the 29A7 firmware for end devices.

I cannot figure out what is the difference of set up between my radios.

Any help will be very welcome.

Have a nice day!

Check the SP time values on the Router and Coordinator. They should be set to match the longest time your end devices are sleeping.

Thank you for your support!