sleep mode incorrect

But another question:
If I convert a routor to an end device, the sleep mode of the new end device is 0-No Sleep. Then it can not join the network again.
If I convert an end device to a routor, the sleep mode of the new routor is 4-Cyclic Sleep. Then it acts as an end device but has a routor firmware.
All the OTA firmware updates are done with same IDs and same channels.
Why is this happenning? [] What can I do to make it ok? [] Any help is welcomed, thank you!