Max network speed is only obtained with multiple simultaneous file transfers.

Hi, I bought a pair of MA2500D and have a question about the transfer rates. I have a 2.5 Gbps home network and can send files between two computers (each equipped with a 2.5 Gbps ethernet port) across two 2.5 Gbps switches at the maximum speed of 2.5 Gbps. I added the two MA2500D bypassing one of the switches and saw transfer rates of about 800 Mbps for a file transfer of the same file I sent earlier through the ethernet cables. This is about a third of the speed that I get with ethernet. I then sent two files starting the transfer back to back and achieved about 1600 Mbps through the MA2500Ds. Adding a third file did not significantly increase the total transfer rate.

I saw a 1.6 Gbps total transfer rate, which is already a good transfer speed, although less than I can see via ethernet, and I believe there is a 2.5 Gbps port on the MA2500Ds. Based on the above observation, I wonder if there is a channel system in which a single file transfer is restricted to a single channel. Each channel has limited bandwidth, and combining all channels creates a total transfer rate of 2.5 Gbps. That picture would be consistent with my observation. Can you tell me if that is the case, or is there another explanation?

To add some info and further observations: I use the standard settings the devices come with. The PHY rate measured by both devices is about 3590 Mbps for the off-diagonals (0-1, 1-0), otherwise 701 Mbps (0-0, 1-1). Sometimes at the end of a file transfer, the transfer rates climb suddenly to 300 MBps (2.4 Gbps). So it's possible to run near the limit of 2.5 Gbps. Also, while transferring a file at 1Gbps to my computer -that rate is limited for unknown reasons, see above- I can run a speed test in parallel and see the maximum 1 Gbps rate from my ISP in addition to the file transfer of 1 Gbps, totaling 2 Gbps.

What also surprised me was that the rate for simultaneous file transfer in opposite directions is very low, typically 10 MBps in one and 15 MBps in the other direction. This is not the case when using my ethernet connection, which can maintain the total bandwidth of 320 MBps and divide it between the two directions.

So the problems I am stuck with are a limited file transfer rate and a very limited transfer rate for simultaneous file transfers. Can I change anything in the settings to bring these transfer rates up? The device can reach 2.5 Gbps, as I have seen several times, but only briefly during file transfer or with a combination of independent data streams.