We are getting the No Server issue and Lost Connection to Server messages frequently.
Lost Connection to Server:
The Dashboards size are around 1 to 100MB size and doesn't has any complex calculations in the frond end just used Sum() & Count() kind of expressions. We have set the Session Timeout as 1800 seconds for this. Still we are getting this message with in 3 minutes.
When we checked the CPU usage is around 50% and memory is availability is more than 32 GB. When we refresh the browser again we are getting the list of Dashboards in Accesspoint. We are getting this message randomly. Restarted all QV Services & finally rebooted the server also. The issue still not resolved.