Probably you are getting a timeout from your web server while waiting to establish a connection to the database. You should at least add the connection properties "socketTimeout=1000" and "retriesAllDown=3" or some other low values. The defaults are too high for the situation where no server is listening in any of the pointed ports; those would result endless waits and each server would be tested 120 times before actually failing to get a connection.
So, my guess is that you don't have any server listening in any of the hosts. If that's not the case, can you paste the stack trace from the error you're getting?
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