Why is my wireless LAN suddenly transferring files so slowly?

[Papageno]

I can't figure it out. It used to transfer files at about 27 megabytes per second and now I'm lucky if I get 7. Nothing has changed that I can tell, apart from the fact that I updated the hosting PC's UEFI BIOS, and maybe installed a couple of Windows 11 updates. The receiving computer is running Windows 10 with the extended security updates till October sometime. The sending computer is plugged into the wireless AC router, and the receiving one has a USB-plugged in wifi (N) adapter.

Sometimes the transfer will just crap out with an unspecified network error--not too helpful. Anything I should check in the UEFI BIOS of the newer machine maybe? Or the network control panels on both computers?

 

[Papageno]

Have your link rates changed at all?

Thanks for the reply, but I'm not certain what that term means. Where in Windows 10 Pro (receiving PC) and Win 11 Home (sending one) would I check that? I haven't consciously done anything to either PC apart from install OS updates and on the sending one, the UEFI BIOS.

If the link below describes how I should check this on both machines, I will do that and report back. I know that nothing has changed in terms of hardware. All I can think is that somehow the wireless spectrum nearby is a lot more crowded/noisy suddenly.

https://www.tp-link.com/us/support/faq/2265/

 

[Papageno]

The wireless adapter on the receiving machine says it's 144.4 Mbps. This strikes me as low. Maybe it needs a new driver or something, because the specs say it should support up to 867 Mbps on the 5 GHz band.

 

[Papageno]

@continuum I'll have to try that on the other machine (the one depending on wifi). On this one connected by ethernet cable to the router the Speedtest.net results are 658+ Mbps down and 42+ up.

I looked into downloading a new driver. The model of wireless adapter is a TP-Link Archer T4U Plus and does support Wireless AC after all. I found a new driver but it looks like it's using a much more recent Realtek one.

But after all is said and done I feel totally silly, because it turns out the stupid thing had at some point connected automatically to the 2.4 GHz band and not to the 5 GHz one. I corrected that and configured it so it wouldn't connect automatically to the 2.4 GHz band.

 

[Papageno]

Aargh. Last night the same Windows 10 Pro machine lost Internet connectivity for no discernible reason. When I went over to it, logged into Windows etc. it identified the 5 GHz band (from it seemed to have spontaneously disconnected) as having "no Internet" even though the other, Ethernet-connected machine suffered no lack of connectivity. The USB3 connected wireless adapter's light on the Windows 10 machine was blinking slowly when I made my way over to it.

I couldn't get it to reconnect to the wireless network so I rebooted the machine and it connected again to the WLAN just fine.

 

[Papageno]

I would check for a driver and firmware update for the WiFi hardware.

Yeah, I looked into that last time around and there is a downloadable driver for the adapter but it's older than the Realtek driver it's using now. Still, the older driver is from the manufacturer (TP-Link).

 

[Papageno]

I’ve seen this happen - usually it’s not one thing but a combo. Biggest red flag: you’re sending from AC Wi-Fi to an N adapter. That alone can bottleneck hard, especially if interference increased.After BIOS/Windows updates, check NIC drivers mine got downgraded once and killed speeds. Also verify link speed in adapter settings (sometimes it drops). Try forcing 5 GHz on the router if possible.
The random dropouts sound like signal instability or power saving settings disable “allow computer to turn off device” in Device Manager.
Not 100% sure it’s BIOS-related, but I’d start with drivers + Wi-Fi limitations first.

Actually the adapter is supposed to support AC as well. Good idea though about checking the power saving settings.