Application Server agent becomes unusable with several communication related errors with SQL Server DataServer

Application Server agent becomes unusable with several communication related errors with SQL Server DataServer

The errors show up in the AppServer server log file.

Application Server connects to SQL server database

The error 14959 can also occur when taking Windows AM Virtual Snapshot or other backup software like  BackupExec to perform nightly VMWare bare-metal snapshots for virtual machine.  During the time of backup snapshot the windows freezes for some seconds to keep the consistencies of the backup image.  This causes the communication link failure between Progress client connected to the MS SQL Server through MS SQL Server DataServer.

TCP Chimney Offload feature is enabled on the server. This feature is enabled by the Windows Server 2003 Scalable Networking Pack.

To fix the error during the backup of Windows or Windows VM snapshot, disconnect the AppServer or WebSpeed broker by stopping the broker.  Restart the broker again after backup is done.

To disable the TCP Chimney Offload feature refer to the Microsoft article 942861 below:

"General Network error", "Communication link failure", or "A transport-level error" message when an application connects to SQL Server
https://support.microsoft.com/en-us/help/942861/general-network-error-communication-link-failure-or-a-transport-level
 

References to other documentation:

Microsoft Article(s):
"General Network error", "Communication link failure", or "A transport-level error" message when an application connects to SQL Server
https://support.microsoft.com/en-us/help/942861/general-network-error-communication-link-failure-or-a-transport-level

Disabling the TCPChimney During IIS 6.0 Troubleshooting
http://blogs.msdn.com/b/chaun/archive/2008/02/20/disabling-the-tcpchimney-during-iis-6-0-troubleshooting.aspx