TCP/IP DDM resulting in CPE3447, CPD3E34 with errno 3447

We are doing a CPYF of a TCP/IP DDM file.
We are getting:
CPE3447 - A remote host did not respond within the timeout period.
CPD3E34-DDM TCP/IP communications error occurred on connect() to
Application Server
 Error code (errno) 3447 was received.
CPF4404, CPF9162, CPF5739, CPF2813, CPF2817, CPI9153

If we retry then it works.  Thus one possible solution is to try once, if
it fails, wait a spell and try again.  Could be QED by the CL.  However the
powers that be want me to try to find out why we are getting the timeout.

Target system: V5R1, cum=TL01302
Source system:  V4R5, cum=TL00231

Definitions:
Source system - The system initiating the CPYF.  They have the DDM file.
Target system - The system with the actual PF.

I checked the TCP/IP DDM attributes.  There are no timeout values like
there are in FTP.

There is a VPN between these two systems.  The source system is a customers
of ours.

Rob Berendt
--
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
Benjamin Franklin