I've recently landed a pretty sweet job where I support a small team in a trading environment. We handle the tech issues that pop up, and right now, we're experiencing some unusual lag with our trading software. While troubleshooting with Wireshark, I noticed something odd: when connected via wired Ethernet, about one-third of the packets show TCP errors, particularly retransmissions and duplicate acknowledgments. However, when one of our brokers switched to a WiFi connection, their packet capture showed no such errors, even though their traffic level was higher than those on wired connections.
All affected laptops are Lenovo P1 models from various generations, and the issue seems consistent across these machines. I've tested connections through docking stations and directly into the PCs while even trying different networks—both in-house and outside the company—but WiFi remains error-free. I took my PC home and ran the software there without the same errors showing up.
This leads me to suspect potential NIC driver issues, but I currently lack prior captures for comparison, and while drivers are updated, it seems to have been a persistent problem for others too. Has anyone dealt with similar TCP errors? If so, what steps did you take to resolve it?
3 Answers
Are all the laptops running Windows 11? If they upgraded from Windows 10, did you notice if these errors were present before the upgrade? It might be worth investigating if the OS change coincides with the TCP problems.
You might want to try disabling 'Checksum Offloading' in your network adapter's properties through Device Manager. This has been a common issue with many NICs in the past and could resolve those TCP errors you're seeing.
Just a heads up, you'll also want to look for settings related to 'Generic Receive Offload' or 'Large Receive Offload.' These can also create similar issues because they attempt to optimize packet processing, but sometimes the NIC firmware just can’t handle it.
Are you using docking stations? I've had my share of headaches with Realtek drivers in docks. Sometimes the issue lies not with the NIC but rather how the dock interacts with the laptop. It could be worthwhile to check the chipset and install the latest drivers from Realtek directly.
Yes, technically it's a Philips monitor dock. I've plugged directly into the PC too, so I'll experiment with using a USB-C dongle as a test since that helped someone else. It’s frustrating, though, because I can’t just switch everyone over to dongles.
Just a reminder to make sure you're on the latest Realtek drivers. If you’re still having issues, consider downgrading to older versions, but keep in mind your regulatory requirements!
Thanks for the suggestion! I'll definitely check that out.