2.5G Dual RJ45 Port PCI-E Network Card with RTL8125B Conrtoller, QFly 2.5Gb Ethernet Adapter Card Compatible with 100/1000Mbps/2.5G, Support Windows/Linux

I picked up two of these QFly 2.5G dual-port PCIe cards and they’ve been phenomenal for the price. Easy install, solid performance on both Windows and Linux. The only hiccup was with PCI passthrough — the Realtek RTL8125B chipset doesn’t play nice with virtual machine passthrough. I had to fall back to a VirtIO setup for my router VM. Not ideal, but it works — and that’s on the chipset, not the card. Pros: Reliable 2.5G speeds Plug-and-play on most systems Great price Dual ports on a PCIe x1 slot — perfect for compact or low-slot systems Cons: Realtek chip has known passthrough issues in VM setups Verdict: 5 stars. Great card, just avoid it for passthrough-heavy virtualization.

I purchased this card for an existing Ubuntu 20.04 LTS Xen server. It works great, and fits very nicely into a 1U server chassis. But, the big problem is drivers. The manufacturer download site is laughable. The only option is to download a source version of the driver, once you find it, and then rebuild the driver and your kernel to include it. It would be one thing if this was for a really old or really new OS, but Ubuntu 20? Fortunately, I found a project on GitHub (awesometic/realtek-r8125-dkms) which builds and packages the driver. All you need to do is to install DKMS, and then install the downloaded .deb file, and all is well. In summary, this is a great little card, marred by terrible driver support. Apparently Ubuntu 22.04 LTS may include RTK8125 support built-in, but for older OSs, forget it.

If your thinking of using this for SMB multichannel it wont work at full speed. Seems the card can only handle 1.75Gb when using both ports at the same time. Other than that the card works great.

Great card for the money. My onboard card failed and this did the trick and saved me.

Works great it does have a blue led that blips along, not great for glass or open cases that you’ll keep in your room. Works smooth on Linux btw.