Co-coordinator changed its operating channel, how do I make other nodes in that channel?

I have update the firmware of my Xbee nodes. And after that the Coordinator changed its operating channel!And now my other nodes are not “visible” to Coordinator when done network discovery. So how do I make them on same operating channel? isn’t this is handled automatically?

And one more weird thing I observed, other nodes are communicating with their destination devices. How this is possible? Coordinator is on different channel but have same PANID as other nodes, it means network is formed without Coordinator? And if network discovery is done, all nodes are “visible” except Coordinator!

Anyways I solved this. I done a network reset (NR) on all nodes and then nodes connected with this new PAN ID.

But I am curious what would happened if this was in “real world”, I was testing in lab. Don’t Xbee themselves search for the Coordinator?

And the nodes were communicating because peer to peer communication is allowed.