Low speed on 10Gbit network with Synology

[Enquiries]

My new setup:
Synology 1621+
Intel X550 10Gbit card
4 x WD RED Pro each 16 TB in SHR
1 SNV3410 800 SSD for cache

When i tranfer a large file from my WD SSD 960 pro 2TB in my PC to the NAS i expect a tranferrate from about 600 MB/s (in one of your videos you sugested about 200MB per actual drive)
I do not get a steady line and it fluctuase between 180 and 280 MB/s
What settings could be wrong on my NAS?

[ed]

To check if Jumbo Frames are enabled, you can go to the Control Panel in the Synology interface, select "Network," and then click on the "General" tab. From there, you should see an option for "Jumbo Frame." Make sure that it is set to the appropriate value (usually 9000) and that it is enabled.
If you want to achieve faster transfer speeds, you may want to consider using SSD or even NVMe storage, as these tend to have much faster read and write speeds than traditional hard drives. However, keep in mind that SSD and NVMe storage tend to be more expensive than HDDs, so it may not be a viable option for everyone.