Can you download the log from the GUI in Status > Hardware > Log then click on the Download button then use a WinRAR or other program to view the log file and look for the test.log and search the "hdparm" and check the speed of the volume in the form of "sda or other" and also look for "ifconfig -a" to check the speed of the nics to make sure they are at 1000Mb/s and if there are any dropped packets.