I have an 800 Mbps home internet plan and two computers connected by Ethernet. Speed tests show that both connections can reach roughly 500 Mbps, but real downloads are very different: one computer gets around 300 Mbps while the other only manages about 70–80 Mbps. What could be limiting the slower computer?
4 Answers
Test the computers one at a time and verify whether the slow speed happens on every site or only with a particular download. Also check whether a router feature such as traffic prioritization or bandwidth limits is affecting one device.
Start by swapping the Ethernet cables and router or switch ports between the two computers. If the slow speed follows the cable or port, you’ve found the problem. If it stays with the same computer, check that machine’s Ethernet adapter and network settings.
The slower computer may only have a 100 Mbps Ethernet adapter, or it could be connected through a 100 Mbps port, cable, or switch. Check the negotiated link speed in the computer’s network settings; it should show 1 Gbps rather than 100 Mbps.
If the speed test is similar on both machines, the local connection may be fine. Download performance also depends on the server you’re downloading from, and some sites limit each connection. Try several different download sources, or compare the same file on both computers.
That makes sense. One of the computers is older, so I’ll check whether its network adapter is limited to 100 Mbps.