I can't access my Router remotly

Hi, have a central office and many branch-offices, all of them with a mikrotik Router.
Well The problem is that locally i can acces my routers via winbox, but when I try to access from the central office to one of the other brach-office routers via winbox I can’t, there is a messagge that says : Could not connect to IP ADDRESS - network is unreachable, the same thing happen viceversa, from the branch-offices to the central. Could anyone helpme please I’m new in this, the version of the RouterOS is 2,9,27.

Thanks,