MySQL database sync options What are some of the good options to sync two or more MySQL databases of the same schema, situated at different locations; reliably?

We have four database in four different locations.

we tried using the generic master master replication but the link breaks again and again leading to inconsistencies.
There are many things that can go wrong in Master-Master.  Use Master-Master, but do not write to both masters.  Pick one for all writes; leave the other one for failover.