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Understanding mode switching in Realtek RTL8812AU 802.11ac Windows drivers

Understanding mode switching in Realtek RTL8812AU 802.11ac Windows drivers

So you just received your brand new 802.11ac USB adapter, capable of 867 mbps, and you plug it in and run a diagnostic program and wait, what’s this? It says it is a USB 2.0 device? You run another diagnostic program and it says the same thing! You know that USB 2.0 is only capable of 480 mbps. So the adapter is not really 867 capable after all….hmmmmm...but wait, actually it is.

The reason this happens is because the driver switches between USB 2 and USB 3 modes as needed.

These devices are backward compatible with older networks that have speeds below 480 mbps, such as 802.11n 150 and 300 mbps networks. The default mode of these USB 3.0 devices according to diagnostics is USB 2.0. When you are not connected to any network, this is the mode that will be displayed. When you connect to an 802.11n network, or a 1T1R 802.11ac network, the adapter will stay in USB 2.0 mode because the max speed of 480 for USB 2.0  is more than your network connection rate.

But connect to an 802.11ac network above 480, such as an 867 mbps 802.11ac 5 GHz network, and then check diagnostics again. Now it shows USB 3.0 as the mode. The chipset uses smart switching to go into either mode depending on what type of network to which you are connected.
3 comments on Understanding mode switching in Realtek RTL8812AU 802.11ac Windows drivers
  • David Kamaunu
    David Kamaunu

    Modes can be set at ‘Auto’ (Default) or USB1, USB2 and USB3 in Windows 10 by way of the Device manager and ‘Advanced’ Tab for properties. Scroll down and you will find the property and msgbox to enter values. I changed mine to use 802.11ac and 5Ghz mode first along with VHT TX/RX & HT TX/RX to maximize throughput from my own dual-mode router that is in the same room. 5Ghz besides having less traffic from less users (and less collisions) does best LOS (Line Of Sight) with few barriers to reduce it’s link budget. Also there is a misconception that proximity is only beneficial to throughput. This is not true. There is a point at which reducing the distance between a wireless NIC and an AP have a deleterious effect. Meaning it will negatively effect your reception by getting too close to the AP/Gateway. I hope this answers some questions in the community

    April 26, 2022
  • Muhammad Abdul-Khabir
    Muhammad Abdul-Khabir

    How do you force to be in USB 3.0 mode? I want to use the higher speed to stream between 802.11ac 5Ghz devices and need the 3.0 mode, but windows just says “this device can run faster if connected through USB 3.0”. It’s only doing around 400mbps rather than a 600mbps as it’s a direct line of sight connection between the two, they are literally just 3 feet away from one another with nothing in between.

    July 14, 2020
  • Customer

    Is it possible to disable this switching feature? I don’t need it

    December 10, 2017
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