Connection verification failed for data source - connection refused

You need to find out where the problem is. Otherwise, everyone will just be guessing.

(Update, I added points 3 and 4 right after initially submitting this reply. I hope you may see that before responding, if perhaps you saw the response as sent to you from this forum when I first posted it, as this update will also be sent.)

1. First, let's find out if the problem is really in CF or not, or on the CF machine or not. Have you implemented any mysql client on the same machine running CF? And can it connect to the mysql? If not, then the problem is NOT in CF but in either the machine running CF, the machine running mysql, or something in between (perhaps a firewall you are not thinking of).
2. If you CAN connect to it from within a mysql client on the CF server, are you using exactly the same connection values (server, port, username, and password) as being used in CF?
3. Are you telling the CF Admin connection to the DB to use SSL, TLS, or any other form of encryption?  Even if not, it could be implied by the port you are using for MySQL. What is it?
4. And in either case, what is the JVM you are using (that CF points to)? It's listed on the CF admin"settings summary" page. That may play a factor in what is supported, in a call from CF to any resource secured by TLS/SSL.

Let's hear your answers to those before making still more guesses. (Or maybe someone else will jump in seeing an answer already.)