Not reaching 2.5gbe Speeds from Mac to Unraid NIC

[JamesBondPPK]

Hi, 

I recently purchased a 2.5gbe nic (Realtek 8125) for my server (had an issue where the onboard nic died and needed a back and took the oppurtunity to do some redundancy and upgrading). 

 

So I setup the nic in one of the PICe x1 lanes (Gen 3, so it should be fast enough) and have it so I can directly connect to the server. The nic is not bridged or bonded, has its own IP range (xxx.xxx.11.x oppose to the onboard that connects to the network which is xxx.xxx.1.x) and I manually assigned an IP4 to computer when I connect. MTU is left at 1500 since 9000 didn't seem to make any difference. There is no switch or router between the computer and the server and I am using a CAT 6a cable. Everything is talking, but speeds aren't consistent.

 

The issue I am having is when I connect my MBP M1 (usb-c to ethernet 2.5Gbe adapter) directly to the nic, I only get 1.5gb/s sending data, but when the connect is reversed, I get 2.35gb/s. If I plug in my windows PC instead, I get 2.35gb/s both ways. To make things more confusing, if I increase the streams ("-P") to more than 6, I get the full 2.35gb/s both ways on the MBP.

 

So it doesn't appear to be a hardware issue or a driver issue on the server. I think there might be an issue with the way apple set things up, but I really don't know.

 

Anyone have any ideas? Or solutions to similar issues? 

 

TIA

 

 

[JorgeB]

It's a known issue with some Realtek NICs, some workarounds here: