Troubleshooting 2.5 Gbps Network Speed Issue with NAS and RT-AX86U Router

[Stylishh1]

I have a RT-AX86U router with one 2.5 Gbps port that I can configure either for WAN (internet) or LAN (internal network). In my setup, I want to connect it to a NAS server with Proxmox, which also has a 2.5 Gbps network card (FENVI 2.5G PCI-E) and SSD drives for faster file transfer. And that's exactly what I did.

When I ran tests with iperf3, it turned out that the connection only reaches a maximum of 1.46 Gbps, which is unsatisfactory to me.

Troubleshooting:

• I assumed it was the fault of the Chinese network card in the NAS server, so I ordered the TX201 TP-Link, but the same issue occurred.
• I tested the FENVI 2.5G PCI-E card from the NAS server in another computer running Windows, but the same issue happened.
• I installed Windows 11 on the NAS server, and again, the same problem.
• I replaced the cables with other CAT5e cables (tested 5 of them), but the same issue.
• I ordered 3 flat CAT7 cables, and once again, the same issue.

I’m now at a loss. On the router, I can see that the port is operating at 2.5 Gbps. On the NAS server, when I run the command to check the speed ethtool enp1s0 | grep -i speed, I get the result: Speed: 2500Mb/s

I’m really stuck and don’t know what to do next.

 

[bbunge]

You may have discovered, as I have, that the 2.5 Gb port on the AX86U is less than optimal. Same with the 2.5Gb port on the AX86U Pro. I have tried to use those ports for Ethernet backhaul with tested CAT 5e cables and, in time, have had the connection fail. Even connecting the 2.5 Gb port to a 1 Gb port has caused connection issues never mind the data transfer rate.
So, best of luck with your endevors. I doubt that you will find a solution. May be better off to stick with using 1 Gb as this is sufficient for most home networks.

 

[ColinTaylor]

Running the iperf server on the router is not a valid test because iperf will become CPU limited. You need to test LAN to LAN transfers, which admittedly is quite difficult as you'd have to use multiple clients and aggregate the results.

You will also get better results from iperf if you use parallel streams, e.g. iperf3 -c 192.168.1.1 -t 120 -P 8