4 MB/second transfer with USB 3.0 HDD Docking station

Have owned this docking unit for less than a year and it is giving me slow transfer speeds.

I am using the same Western Digital SATA 6 drive and have historically gotten between 30MB/s and 50MB/s.

For some reason, I am down to 4Mb/s.

I completely formatted the drive.

Any suggestions? Thanks.