A patch for the plug-in has been provided which would exercise the channel, by sending messages at a periodic interval. In this way the socket would be active, and the network would not close the socket. In addition, the plug-in would generate a job-mgr-change-state that also triggers the job manager to send MSG_FLUSH_CHANNEL_MSG at regular interval. The channel exercise message is send by the plug-in by default every 180 seconds. This can be configured in the plug-in options to a different value.
Please contact Support to obtain the patch to address CR# 28971
Waiting for a fix in a future release of NetVault Backup.