When several SAP Syncs are running in parallel on the same server, you receive the error message above.
If you monitor how many connections/ports are in use during an SAP Sync (netstat -ano | find "<IP address of the SAP host>"), you will see hundreds of connections with the status "TIME_WAIT". If several SAP syncs are running on the same server, the number of connections is multiplied accordingly.
This is a product defect in the 7.1 line.
Do not run SAP Syncs in parallel on the same server.
The SAP Connector has been optimized in the 8.1 line and creates only 2 connections/ports per sync.