On 14.5 SDK attempted:
But, both failed displaying the same error dialog and console message:
"Failed to connect to Xilinx hw_server. Check if the hw_server is running and correct TCP port is used."
hw_server is used with the TCF infrastructure for debugging and it only supports Digilent and has to be launch manually from a shell.
The 'Auto Detect' option always chooses the TCF flow when the Digilent cable is plugged in.
If you do not want to use the TCF infrastructure, you must change the JTAG cable pull-down menu from Auto Detect to 'Digilent USB Cable' and resolve the error.
This change is found from SDK's Xilinx Tools -> Configure JTAG Settings. Again, changing from Auto Detect to Digilent USB Cable resolves the issue.