CSS326 is literally the worst layer 2 switch I have ever seen. But excellent product as layer 1 switch.
here is some simple review.
G4560+Z270+Intel X550T1+Windows 10 Pro as server
6800K+X99+Intel X550T1+Windows 10 Pro as client
cable: CAT6A approximate 15M from server to switch and from switch to client
Module: S+RJ10 x2
iPerf on windows
SMB3 file copy from Intel 600p 256G to Toshiba XG3 512G
iPerf 8 threads, no problem to utilize 10G
SMB copy, not so good
I did some digging, windows failed to use multiple channel for this file copy. Theoretically, windows should be able to detect this is a 10G nic, and start using SMB3.0 multichannel with multiple tcp connections.
But it's windows fault. I'm quite satisfied with my setup.