Why Is My Laptop Wi‑Fi Much Faster Than My Desktop’s Ethernet Connection?

The Ethernet cable is the most likely culprit, even if it’s labeled Cat5e or Cat6. Try a different known-good cable, and inspect both ends for bends, crushed sections, or damaged connectors. Also try another router or switch port.

Update the Ethernet adapter drivers using the exact package for your motherboard. Then check the adapter’s link speed and duplex settings. A duplex mismatch or a connection negotiating at a very low speed can drastically reduce performance. If the cable runs through a switch or powerline adapter, test with the desktop connected directly to the router.

There isn’t quite enough information to identify the problem immediately. The operating system, motherboard or network adapter model, cable type, and connection path would help. If a different cable and port do not help, check for damaged ports, router firmware updates, and BIOS updates. A separate PCIe Ethernet or Wi‑Fi adapter can also confirm whether the onboard adapter is failing.