Hi Hariprasad,
I went through the sniffer log and found that there's a device with the short address 0x8D50 that doesn't seem to be receiving the Route Request commands from the coordinator, and its Route Request commands aren't reaching the coordinator either.
In the Link Status packets, after a certain point, the coordinator no longer reports the 0x8D50 device, while the latter still reports that the coordinator is in range.
Could you please check for possible physical obstructions and/or interference from other devices that could be causing your coordinator and router to be missing messages?
Best regards,
Sebastian