Issue with Storage Devices - QNAP NAS - StorageAPI credential failed : Test connection is failed

Issue with Storage Devices - QNAP NAS - StorageAPI credential failed : Test connection is failed

We have a number of QNAP NAS's which I am monitoring as OPM Storage Devices. The devices add in without error and monitor ok, but I get random credential failed errors mixed with credential test passed all through the day. When I do a manual test of credentials it always passes. There is no known connectivity issues with the NAS's and is only happening with the QNAP branded ones. Is this a known issue with QNAP and OPM or any ideas on a fix for this ? 
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