Question about T7 Shield - 566125

Hello friends. I have large video files which I need to back up so was very happy when this came out. I have an Aurora R9 Alienware PC (USB 3 and 3.1 gen 1 and 2 x gen 2 ports so not a spec issue). I ordered this about a week ago and all week I have been trying to get ‘reasonable speeds’ (not looking for the max which is stated because we all know this can be impacted by a number of things!) but I do not get more than 159Mb/s and that was only once which allowed me to transfer some files over. I know am back to what I was getting originally which is in the region of 30-40 Mbp/s! I have changed drivers, reinstalled drivers, enabled better performance with write cache but still no change? I am transferring from a 7200 rpm HDD to this SSD but I cannot believe the HDD is the bottleneck? I have done various speed test and crystal disk test which show much higher read and write speeds but that is not shown with actual transfers! My files are large 3-4 and over gb so not mini files which can impact the speed. any help or guidance please on what could be wrong? I genuinely do not want to return this but spending 2-3 hours (if I am lucky) transferring files is not good. Thank you vielen danke