If you receive an error (such as “Physical connection is not useable [xFFFFFFFF]”), when connecting to Amazon SQL Server via a Linked Server or ODBC connection, you need to disable the TCP Chimney Offload setting on your on-premise SQL Server. To do so:

First disable the below settings on the calling machine (found in Local Network Connection  -> Network Adapter Properties).

  • IPv4 Checksum Offload
  • Large Receive Offload (IPv4)
  • Large Send Offload Version 2 (IPv4)
  • TCP Checksum Offload (IPv4)
  • UDP Checksum Offload (IPv4)

Then disable the following settings from the command prompt:

  • netsh int ip set global taskoffload=disabled
  • netsh int tcp set global chimney=disabled
  • netsh int tcp set global rss=disabled
  • netsh int tcp set global netdma=disabled

That’s it! You should now be able to connect to Amazon SQL Server.