Speed transfer with my MyBook Duo 8to in Raid 0

Dear members,

i had a problem with my Mybook Duo 8to which is in RAID 0,
the transfer speed (tested with the Blackmagic Speed Test app) are around 140mb/s exactly the same than with my “normal” Mybook 8to (which is not in RAID 0). Or i waited something around 350mb/s…
i use a Macbook pro 2017 with USB C but with an adapter to connect the USB 3.0 from my MyBook Duo.

Do you think it could come from the adapter ? Or do you have any suggestion ?

thanks in advance for your help !!

warm regards
Aliocha

Did you check the data transfer speed of My Book Duo on another computer?

i checked, but this is exactly the same on another computer…
so it doesn’t come from the adapter.
do you have any idea ?
i bought a Duo in Raid to have better speed performance … which is weird because also i remember when i bought it the speed transfer was good…
do you have any idea ?
thanks!

no one has an idea? it’s quite annoyed to have the same speed than a single hard drives with a duo…

do you think that’s normal?
what can i do?