Hi Selvaraj, thank you for using our forum, my name is Luis I am part of the Small business Support community. A apologize for this inconvenience, for this kind of issues I suggest to update the firmware again by the same and perform a factory reset, then configure it manually, if the issues continues, could you please reach out to our Small Business Support Center and open a Service Request to address this issue? One of our Engineers may be able to work with you and diagnose the root cause. You can find the appropriate contact information for SBSC in the below link.
http://www.cisco.com/en/US/support/tsd_cisco_small_business_support_center_contacts.html
I hope you find this answer useful
Greetings,
Luis Arias.
Cisco Network Support Engineer.