1.
Create database, not on localhost but on remote server.
Create user and privileges with grant (remote connection works with success)
2.
alfresco-global.properties changed
3.
mysql connector is well added (when it's not, an error is raised).
The error is still the same.
When I make a volontary error, I've got the "Communication failure" error and when I write the good parameters, the IP of the localhost server is taken instead of the the remote server. It seems that db.url reads db.host but it replaces it with the IP of the localhost server.