It could be that your ISP is blocking UDP traffic with dst port 123 towards your router. Have a look at this thread for a work around: http://forum.mikrotik.com/t/ntp-client-not-syncing/176955/1
It could be that your ISP is blocking UDP traffic with dst port 123 towards your router. Have a look at this thread for a work around: http://forum.mikrotik.com/t/ntp-client-not-syncing/176955/1