I'm running Linux Mint 22.2 on an ASUS X554LJ laptop, and the connection has become unusually slow over the past few months. The issue happens over both Ethernet and Wi‑Fi. Speed tests usually report around 18–20 Mb/s download and 20 Mb/s upload, but actual downloads are often limited to roughly 50–100 kB/s. This is especially noticeable when downloading updates through the system's Update Manager, regardless of which software mirror is selected. Other downloads and websites can also be affected. I recently replaced my old modem with a fiber-optic connection, but the problem remained. When I connect my smartphone to the new modem, it reaches the expected fiber speeds, so the issue seems specific to the laptop. Could this be caused by hardware, Linux configuration, DNS, routing, throttling, or something else?
2 Answers
The fact that speed-test results look normal doesn't rule out a problem with particular destinations. Speed tests use selected servers and may measure a fast route, while package mirrors or other websites could be affected by routing, IPv6, DNS, or a proxy setting. Try comparing the same download in another operating system or from a live Linux session. If it is fast there, the installed system is likely misconfigured; if it is slow everywhere on the laptop, hardware or its network driver becomes more likely.
It could theoretically be traffic shaping by the ISP, but that seems less likely if the slowdown affects Linux update servers while your phone reaches full speed on the same connection. Since the problem happens over both Ethernet and Wi‑Fi and only seems to affect this laptop, checking the laptop's software configuration, DNS settings, routes, and download behavior would be a better starting point.
That makes sense. The phone being fast suggests the fiber connection itself is probably fine, so comparing with a live session should help separate a Linux configuration issue from a laptop-wide problem.