While the Idletimeout is an issue, the primary pursuit needs to be
why the client failed to send any backup data after being given the
Active Files inventory at the onset of the Incremental (presuming it
is an incremental backup).  If nothing found in their scheduler or
dsmerror log, a client trace may be needed to see what they think
they are doing at that point.  Given the client mix showing up, this
might turn out to be a networking issue.

   Richard Sims