Redshift connection fails even when I get success message when I test connection

This has been happening since a couple of days and I can't access my data at all. It was working perfectly before and nothing has changed my end.

When I test connection there is a success message but when I try to synchronize data there is an error message. 

Connection to Connection to rsdb ...... failed [28000][10100] [Amazon][JDBC](10100) Connection Refused: [Amazon][JDBC](11640) etc...

Would really appreciate your help on this one!

Thanks in advance.

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