Routers sudenly disconnect

Hello, I´m new to Zigbee and I am testing a network with 1 coordinator API and 27 routers API. Bus sometimes, for apparently no reason some routers disconnect.

Did anyone face this?

Why is this happening? Is there any configuration on the module that makes it reconect again after certain amount of time disconected?

I never faced this kind of issue. Set JV=0 on the router, (JV - If JV=1, a router
will verify the coordinator is on its operating channel when joining or coming up from a power cycle. If a coordinator is not detected, the router will leave its current channel and
attempt to join a new PAN.
If JV=0, the router will continue operating on its current channel even if a coordinator is not detected.)

If your issue is already solved please update the forum.