10gbe Network troubleshooting

I have two computers connected and I can not figure out why the connection between them is so slow.

Server is a Ryzen 7, AsRock Taichi MoBo, and a Melinox 10gbe NIC. Client is a Ryzen 9 3900, MSI Carbon Pro x570, Asus 10gbe Nic. The cables between the two are all cat6 or DAC.

Client>CAT6>RJ45 SPF+ Cage>CRS305-1G-4S+IN>DAC>Server.

When I run iPerf3 between the two computers I only get about 2.8 gbe. What am I doing wrong? Where do I start troubleshooting this bottleneck?

Thanks for your help.

Additional information. Client and server connected directly to each other produce the same results.

SPF+ cages are 10Gtec

There might not be proper support on the server for the Melinox 10gbe NIC. I have been using the INTEL X520-DA2 cards as they are reasonably priced on eBay and very compatable.

Thanks for the reply. I did try using 2 Asus 10gbe cards and got the same result. Could it be that the server (UnRAID) is somehow holding on to old/slower configurations? UNRAID sees the 10gbe card and recognizes the speed as 10gbe.

I have never used unraid so not really sure. It’s build on Linux so it should have broad support. If you have 2 Asus cards you could try direct connecting them to see if the results are the same.

I put both Asus cards in and directly connected them with a CAT6 cable. It was actually just a tad slower. Still around 2gbe. I did also check the PCIe Lanes and they are both on PCIe3.0 x 4…So my understanding that is plenty of bandwidth for 10gbe. (Unraid on the Server/Win10 on the client). I also tried messing with Jumbo frames and that did not change anything either. Still scratching my head.

Thanks for the help!

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Get yourself some cat6a cables which are rated for 10gb. Cat6 is only rated for a gig.

Cat6 cable can support 10G over the distance between 37 and 55 meters depending on the alien crosstalk environment. So as long as it is not a longer run with lots of noise it should work.

The run from computer to computer is only about 50 feet of cable…in the wall. I did run a cable straight from one to the other across the hall and there was no change in speed.

You could try to boot the server into a linux live to see whether or not it’s an Unraid problem maybe? Or have windows on both machines just to check if it’s UnRaid doing something odd

This is my next troubleshooting step. Two Live USB’s and a CAT6A cable. I will report back what I find.