Consultant says that the application server connection to Database Server is somehow lost
Is lost? What does that mean in detail?
SSISDB.dbo[runtime].x) is marked for unload due to memory pressure
SSIS uses some CLR and on memory preasure the runtime get's unload; happens on my servers too (which ist an information message, not an error!) and that never caused any issue.
If the CLR is accessed later, it will be loaded again an you get an info message like "AppDomain 253 (master.sys[runtime].253) created."
Would it causes connection problem between Database Server and Application Server ?
Is it necessary for us to increase the Server RAM
More RAM is never wrong, SQL Server highly use it.