Erradic termination of webclient sessions after undefined times of user inactivity.

Running Sage X3 V12, we are facing problems on all browser and computer platforms: while having open a user session running on any browser or network, useres get kicked out suddenly after a certain inactivity with varying duration.

After cklick message appears saying: Application Error. An error has occured on the web server while trying resolve your request: Session will be closed: Your connection has been lost. Please reload page and re-enter. 

We couldn´t find any workaround networkwise. 

Servers running on Azure.

Any ideas?

Thanks Marcus