>> Especially when there is no activity.
Are you being disconnected from the SQL server after long periods of inactivity? Maybe try opening a file in the WebServer procedure itself, and leaving it open. (Or maybe, there should be no file opened there if you're opening one already.)
This looks less like a NetTalk problem and more like a C9 problem. I know in C9.1 there were a number of fixes regarding SQL - so maybe that's a good option for you too.
Cheers
Bruce