Good morning Will!
I have another question for you:
Why when copying multiple files or single files the transfer goes between 100 and max 500 MB per second?
I have a 1621+ equipped with a 10 Gbe card and, the NAS and my pc are now connected via a 10 Gbe switch, my pc also has a 10 Gbe network card. Also I am using CAT 6a cables.
The NAS then is equipped with 3 Toshiba N300 drives in raid 5 and a 400GB Samsung Evo plus NV me.
I have found this switch that suit my needs: Qnap QSW 2104 2t which in theory should work?
So if you have 3x HDD drives in a RAID5 array then you only have 2x that can be read or written to (in terms of performance). So it looks like more likely than not you are saturating the speed of your drives. At their best HDD’s can do ~250MB/s (this will drop when they get even 20% full) so your max speed would be:
2HDD x 250MB/s = 500MB/s
Adding additional drives to the RAID will make this faster sequentially.
As for the NVMe drive this will not help you with sequential reads, just random. Because of this its something thats really hard to test for.
So QNAP switches are ones that I have really stopped recommending. I have had a ton of clients with really bad luck due to these things. The unifi Switch Flex XG is really solid for the price. Or netgear has a great option (affiliate link)
All clear now! Thanks for your answer!!