My router provides around 100 Mbps over 5 GHz, but my PC is far enough away that I normally use 2.4 GHz. That connection used to reach roughly 35 Mbps, but since last month it has usually been limited to about 4 Mbps. It occasionally returned to normal speed at first, but that no longer happens. Other devices on the same network still work normally, and I cannot connect this PC through Ethernet.
So far I have rebooted the PC, moved the router and equipment, replaced the router, replaced the Wi‑Fi adapter, reinstalled its drivers, disabled adapter power saving, reset the network settings, contacted my internet provider, checked TCPView and Process Explorer, set TCP autotuning back to normal, and tried several other fixes. What else could be causing this?
4 Answers
Distance and physical obstructions can still make a big difference, especially on 2.4 GHz. Concrete walls, nearby wireless networks, and interference from other devices can reduce the connection rate dramatically. Try temporarily testing the PC close to the router. A Wi‑Fi analyzer can also show whether nearby networks are crowding the channel. If the signal is the problem, a better-positioned access point or repeater may help.
Check the USB adapter's specifications and the USB port it is connected to. Some adapters are limited by older USB hardware, and a poorly shielded port or nearby USB 3 device can also interfere with 2.4 GHz. Try a different port, preferably using a short USB extension cable to move the adapter away from the computer, and verify that it supports the wireless standard and speeds you expect.
It is a USB adapter with a fixed antenna, so it does not have a detachable antenna that I can reposition or upgrade.
Since you have already replaced the adapter and reinstalled the drivers, check the adapter's advanced properties rather than only the basic power settings. Make sure the wireless mode is set to the appropriate 802.11 standard, channel width is not forced to a very narrow setting, and the transmit power is high. Also test both 2.4 GHz and 5 GHz while watching the reported link rate; that can reveal whether the adapter is negotiating an unusually slow connection.
The important distinction is whether the Wi‑Fi link itself is slow or whether the internet connection is slow. An Ethernet test would normally separate those possibilities, but since that is not available, compare the adapter's negotiated link speed and signal quality in its status window. If the link rate is very low, the issue is wireless signal, interference, antenna placement, or the adapter rather than your provider.
Another computer connected by Ethernet reaches about 100 Mbps, and other devices are fine, so the problem appears to be limited to this PC's wireless connection.
I already tried moving the router and equipment, and the router has a clear line of sight to the adapter. I also live in a private house rather than a dense apartment building.