I partly solove the problem, but...I changed the hostname temperorily to other rather than prod1 and used netconfig to set an ip for the robot. Then network works. It seems that the hostname of the robot is colliding with other pc at NUS. So I change the content of HOSTNAME, hosts, host.conf and expect the hostname will be changed permainently. But after reboot, the hostname changed back to prod1 as well as the content of HOSTNAME. Could you please advice on how to work out this problem? Lots of Thanks. BTW, maybe #/etc/init.d/network restart should be #/etc/networks restart