Polling engines frequently doconnecting with DB

Hello friends, 

Currently i'm working on Orion 2019.4 version . In my environment there is issue of frequent disconnection of APE from DB when restart the services it goes well. but after 2 3 days same situation arises. Acoording DB guys there is not query in the hang state. 

what could be the reason behind this? Kindly help on this.