Config up NTP client:
/system ntp client set primary-ntp=IP_ADDRESS secondary-ntp=IP_ADDRESS mode=unicast enabled=yes /system ntp client print
You may obtain your closest NTP Server’s IP address from this site www.pool.ntp.org.
Do not forget to set the firewall!
For general way, add this at the top of the input chain firewall filters:
/ip firewall filter add chain=input connection-state=established action=accept add chain=input connection-state=related action=accept add chain=input connection-state=invalid action=drop
Now the router will accept packets that are part of connections it started. When it queries the NTP server, the reply will be permitted. The NTP server sending it something out of nowhere will be blocked.
