My router normally provides around 100 Mbps over 5 GHz, but my PC is far enough away that I usually connect on 2.4 GHz. That connection used to reach roughly 35 Mbps, but since last month it has been limited to about 4 Mbps. It occasionally returned to normal speed at first, but that has now stopped. Other devices on the same network still work normally, and I cannot physically connect this PC by Ethernet.
So far I have rebooted the PC, repositioned the equipment and router, replaced the router and Wi‑Fi adapter, reinstalled the adapter drivers, disabled power saving for the adapter, reset the network settings, contacted my provider, checked TCPView and Process Explorer, and set TCP autotuning back to normal. None of this helped. What else should I check?
3 Answers
Since the adapter is USB, check its exact specifications and which USB port it is plugged into. Some inexpensive adapters are limited by USB 2.0 or have poor reception, and a damaged or marginal adapter can fall back to very low link speeds. Try a different USB port, preferably one that does not place the adapter behind the PC or next to other USB devices, and check the adapter's negotiated link speed in its status or driver utility.
Because other devices reach normal speeds, the internet connection itself is probably fine. Check the adapter's current connection rate, signal strength, and whether it is connecting with an unusual mode or channel width. Also test the PC with a known-good adapter placed close to the router; that separates a PC configuration problem from reception or USB hardware limitations.
Distance, walls, and nearby networks can still cause a major drop on 2.4 GHz, even if the router appears to be in clear view. Try testing the PC temporarily closer to the router. A Wi‑Fi analyzer can also show whether nearby networks are crowding the channel. If the signal improves at close range, a better antenna, access point, or repeater may help.
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