My laptop can connect to my home network using 802.11ac just fine.

However, according to Windows, my Edimax AC1200, only connects to the network via 802.11n.

This is despite the fact that the product claims support for 802.11ac:

USB 2.0 Type A Wi-Fi dual band adapter supports 802.11n & 802.11ac maximum wireless speed up to 300Mbps on 2.4GHz band or up to 866Mbps on 5GHz band

This happens even if I restrict the Wireless Mode to 802.11ac in Device Manager.

I don't understand what the reason is. Why would this happen?

  • That's a rather odd claim for a USB 2.0 device to make, since the USB port maxes out at ~480 Mbps link rate (~350 Mbps useful rate). – grawity Sep 11 '17 at 4:44
  • @grawity: You might be onto something... do you think the specs are wrong? For what it's worth, their own site says the same thing, so if there's an error, it's not Amazon's... and I've tested it in a USB 3.0 port and there's no difference. – Mehrdad Sep 11 '17 at 4:46
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    The specs are probably correct in the sense that the Wi-Fi chip can negotiate AC rates – it just can't push data over USB that fast. (Like those AC access points with only a 100 Mbps Ethernet port...) Though of course it depends on what "useful" speed can be reached at 866 Mbps AC, but in general I think it's still more of a marketing trick. – grawity Sep 11 '17 at 4:56
  • @grawity: Aw dang, I see :\ what's weird is I thought you need big antennas for that kind of speed, so I'm even skeptical they can reach that rate in the chip in the first place, but yeah. Do you think that's the cause of this or is it unrelated? I'm not sure how Windows reports the radio type... – Mehrdad Sep 11 '17 at 5:01
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    Maybe not necessarily big antennas (I think the minimum size depends on the radio frequency, not on signalling speed – a small antenna would be fine for 5 GHz as long as it receives a strong signal), but... I'm guessing it won't have the specs for MIMO, for example. – grawity Sep 11 '17 at 5:06

Edimax support said that the 802.11n is a "typo" (which you can verify by checking the reported rate is over 300 Mbps) and that the 867 Mbps is the link speed to the router, not to the CPU.

  • I should also add they were very friendly and quick to respond. :) – Mehrdad Sep 11 '17 at 20:27

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