We brought the machine to the service center and they replaced a board. So, this issue really needs a part replacement and nothing we can do by ourselves. All features are now working. But, I am not sure what's going on in there, the IP setting will change periodically as if I have set it to DHCP when in fact I have set it to Static.
Looking through the router, it is also listed as DHCP. I'm very sure I selected Static. In the CentreWare it is listed as "Manually". But in the router it is DHCP. We may send it back to the service center.