奇怪的间歇SQL连接错误，修复重新启动，3-5天后返回(ASP.NET)

For some reason every 3-5 days our web app loses the ability to open a connection to the db with the following error, the strange thing is that all we have to do is reboot the container (it is a VPS) and it is restored to normal functionality. Then a few days later or so it happens again. Has anyone ever had such a problem? I have noticed a lot of ANONYMOUS LOGONs in the security log in the middle of the night from our AD server which is strange, and also some from an IP in Amsterdam. I am not sure how to tell what exactly they mean or if it is related or not.For some reason every 3-5 days our web app lose