the server has connection to the internet, i asume ?
Configure it as client /sbin/yast2 ntp-client
Use a public available ntp server http://ntp.isc.org/bin/view/Servers/WebHome
now use this server as main timesource in your network.
If you have no connection buy a decent clock to get your local time signal and read the
manual how to get ntpd to read that beast (most a serial and harmless).