Zigbee radios: When do they re-acquire a coordinator?

I need Zigbee help! I have some DIGI Zigbee radios that associate with a nearby router, and through that to a more distant coordinator. The endpoints sometimes associate with the coordinator by mistake which eats their batteries (coordinator is out-of-range so the radio struggles). How can I guarantee that the endpoints will associate with the repeater and not the coordinator? Also, will powering down the router for a while cause the endpoints to re-associate with the repeater?

I was told that the endpoints will associate with the STRONGEST signal if there are multiple possible associations to be made, but I am not seeing that it is true. Does anyone know?

Thanks in advance for any help!

You can do that by disabling Joining on the Coordinator. That is done by setting NJ to 0.

mvut - Thanks for that info. Let’s say that I have all the nodes associated as I want them, then I set NJ = 0 on the coordinator, and then power fails and comes back on. Will the endpoints re-a€ssociate and potentially find the wrong node to join with? Will the repeater node re-associate with the coordinator as it was before the power failed if NJ is set to zero? That is what I am worried about if I set NJ=0 - that they won’t be able to reconnect after power failure.
Thanks for your help!