There are few reasons will cause copy slow.

1. The speed limitation of HDD , please check the HDD by PC.

2. Please check if you put HDD as 0 degree horizontal or 180 degree vertical. Due to the design of HDD itself, any dip will slow the speed of HDD reading or writing.

3. If you are coping multi HDD at one time, please check if copy slow only happened on few fixed targets. It might because the connector module has damaged by usage. You might connect your local seller to change new connector module or mobile rack.