Setup local NTP servers
Non of routerboards have battery backed up clock so it's good practice to set NTP client on all boards to be able to set proper time after boot. There are many public NTP servers on the Internet but it's always good to have some centralized control of time source and in addition lower load of public servers with the aid of local cache NTP servers.
RouterOS support setting of two servers for NTP client primary and secondary. It's better to setup and use two servers if it's feasible. NTP servers should be located in independent locations with high availability near main gateways.
NTP server could be configured by WinBox in menu System - NTP Server or in command line /system/ntp/server. NTP server service is not included in default set of packages so it needs to be downloaded and installed manually with ntp.npk package.
If package is successfully installed then it can be simply enabled with Manycast support.
Server ip mismatch
In routed network router can have multiple interfaces and ip addresses and NTP server running on such router can answer on different ip address then it received request. Then source NAT should be configured to solve this kind of problem which can result in Bad packet reason = server-ip-mismatch on client side.
/ip firewall nat add action=src-nat chain=srcnat comment="NTP" disabled=no protocol=udp src-port=123 to-addresses=10.10.10.10
