Same problem over here. Actually, the resulting error message is depending on the MySQL servers running over here. There is one on my SSH server and there is another one (called 'MAIN') within the same LAN and connected to another port.
When someone tries to sync. with MAIN from outside he gets the message below (he is able to connect to main, but he is NOT able to sync.).

Now I found that in case both servers are on the same port, the message changes. It gets like in the previous post. So, why is Yog looking at another server when it is about sync. ???