Troubleshooting Network Speed Limitations: My Journey with Zimaboard 432 and OpenWRT x86

Recently, I encountered an issue with my Zimaboard 432, equipped with openWRT x86 software, which I had purchased to serve as my router for multi-gigabit WAN connections. My Realtek RTL8111 NIC delivered a throughput of approximately 1.3 Gbps, significantly lower than the expected 2.5 Gbps LAN speed. Although implementing packet streaming and hardware offloading allowed me to increase the speed to 1.4 Gbps marginally, it remained significantly below the desired threshold.

Seeking a solution, I painstakingly reviewed countless posts and forum threads addressing openWRT speed limitations, but to no avail. My breakthrough came from a Reddit discussion, where I found several users criticizing Realtek NICs due to their subpar drivers. This convinced me to try switching to an Intel NIC.

With high hopes, I purchased a dual-port Intel NIC and connected it to my Zimaboard via a PCIe slot. Disappointingly, the improvement was marginal, with the speed topping at around 1.5 Gbps, with none of my tweaks boosting the performance further. However, I did notice a significant change in CPU utilization.

Desperate for a solution and to achieve full performance, I decided to reconfigure my setup. I connected the WAN to the Intel NIC via PCIe, and the LAN via a USB 2.5 Gbps NIC. The result was promising - I saw speeds reach about 1.8 Gbps.

I was almost there, but one final hurdle remained. To squeeze the last bit of performance out of my setup, I forced the CPU to work at its top frequency using the command:

for a in /sys/devices/system/cpu/cpufreq/policy*/scaling_governor; do echo performance > $a; done

Much to my delight, this last measure proved successful. The full throughput of 2.5 Gbps was finally achieved! My journey of troubleshooting network speed limitations was arduous but ultimately rewarding.

This experience underscored the importance of comprehensive hardware and software knowledge in navigating the complex landscape of network configurations. I hope this account may be a resource for others facing similar challenges in optimizing their network speeds.