As root the cause of the problem has been identified, I will recommend you to try the following two steps:
1. Speak with your database administrator on a possible resolution for this connectivity issue
2. If problem persists, consider reviewing this Knowledge Base article - [Best Practices to Maximize Performance III: Caching](https://community.denodo.com/kb/en/view/document/Best%20Practices%20to%20Maximize%20Performance%20III%3A%20Caching#h.s3p69j7d58pi)
Hope this helps!