Asustor AS5304T slow transfer speed help

[eidolon]

I have an Asustor NAS with 2 x 2.5Gbe network ports. In it are 4 fast hard drives setup in RAID10. On my desktop I have a dual Intel 2.5Gbe network card. Connecting the two is a Tenda TEM2010F 2.5Gbe switch.

On the Asustor I've set up SMB multichannel and link aggregation and on the Tenda I've selected the static link aggregation option for ports 7 and 8.
I've plugged my PC into ports 5 and 6, and the NAS into 7 and 8 (the static aggregations ones) yet I only get 250MB file transfer speeds, I would've thought that I got closer to 500MB

What am I doing wrong?

SMB multichannel enabled

Both NICs showing 2.5Gbe

Link Aggregation enabled

But still only 200MB

 

[eidolon]

I tried all of the different link aggregation options but performance was the same on them all so my suspicion is that link aggregation only really helps if multiple PCs access the NAS simultaneously.
Out of curiosity I’ve swapped to a different 2.5Gbe switch (QNAP QSW-1105) and turned off link aggregation but kept SMB multichannel on. Same results with this switch too.

In this video they get 430 Mb so not sure why mine is so slow.