Server disconnecting ?

Hi, i recently noticed some strange problem with our server setup, occasionally I seem to lose connection even thought the server itself remains available. At these moments I am not able to reach the server using the admin interface untill I logon again in a separate SSH session.

The server itself keeps running in the background, but any task scheduled will fail untill I log on again. Unfortunatly this doesn't last forever Not sure what triggered this, it used to be fine up untill recently so it might be a (ubuntu 16.04) server patch that thinks it's more secure this way...

What's the best way to ensure the server always remains available for all users? Should I give the ownership to root or can I modify this somewhere else?