generic mt7921au

[bjlockie]

I had need of another USB device and I wanted something cheap. :-)
mt7921au Chinese stuff from AliExpress is cheap now.
I bought this: https://www.aliexpress.com/item/1005006200938085.html

$ lsusb
Bus 001 Device 007: ID 0e8d:7961 MediaTek Inc. Wireless_Device

[morrownr]

What's up @bjlockie

I see on the box that it says Driver Free. That always gets my attention. Is it a multi-state adapter?

[bjlockie]

I didn't notice that.
The box also says Dual Band.
I suspect manufacturers do that so they can switch to a Realtek chip but keep the same packaging.
Maybe they already have a Realtek chip and use the same packaging.
I wouldn't have bought it if it didn't say Mediatek. :-)
If I did get a Realtek chip then I was confident AliExpress would give me a refund.
It is a MediaTek 7921au and OpenWRT recognized it right away.
I want to try it as a 6GHz AP. :-)
I had to set the regdomain to get 6GHz though.

MediaTek MT7921AU 802.11ac/ax/b/g/n
5GHz - Channel: 36 (5.180 GHz)
6GHz - Channel: 1 (5.955 GHz)

Why is 5GHz channel 36 but 6GHz is a lower channel (1)?
That seems illogical.

[bjlockie]

I think one of "driver free" or "CD driver" is supposed to be checked.
Neither are checked.
It does include a CD but I don't have a CD drive. :-)

[morrownr]

To check if it is multi-state:

How to deactivate usb_modeswitch:

sudo nano /etc/usb_modeswitch.conf

Change

DisableSwitching=0

to

DisableSwitching=1

sudo reboot

If the adapter still comes as the wireless adapter after the reboot then it is single-state.

I have yet to see a multi-state adapter powered by the mt7921au.

It does include a CD but I don't have a CD drive. :-)

If it includes a cd, it is likely single-state.

I'm always looking for adapters to add to the Plug and Play List. Let me know if this one is something that should be in the list.

[bjlockie]

There's no mode switch file on OpenWrt.
I'd say if there is not a generic entry for any USB adapter powered by a mt7921au then there should be.
This particular adapter has no brand.

I was able to create a 6GHz AP with OpenWrt but my desktop can't see any 6GHz channels.
I have a PCI mt7921k so it should but all the 6GHz channels are disabled in this kernel (6.8.0-39).
I booted an older kernel and the channels are enabled for lubuntu won't let me select 6GHz for the preferred band. :-(
I suspect the channels being disabled is a firmware problem.

[morrownr]

There's no mode switch file on OpenWrt.

Oh, you should have said so. If it is working with OpenWRT then it is a single-state adapter.

I'd say if there is not a generic entry for any USB adapter powered by a mt7921au then there should be.

Let's make one.

I suspect the channels being disabled is a firmware problem.

I suspect it is a regdb problem. It works fine in the EU... DE, FR...

I'm not aware of anyone who has a mt7921au adapter working in AP mode in 6 GHz in the US or CA.

[bjlockie]

I suspect it is a regdb problem. It works fine in the EU... DE, FR...

I'm not aware of anyone who has a mt7921au adapter working in AP mode in 6 GHz in the US or CA.

I can set the AP to any regdb I want. :-)

The problem is my desktop which is a mt7921k has all the 6GHz channels disabled.
When I connect to the mt7921au USB adapter which is a AP set to 5GHz and regdb DE:

$ iw reg get
global
country DE: DFS-ETSI

When I connect to my regular AP my desktop is regdb US:

$ iw reg get
global
country US: DFS-FCC

In both cases iw list shows all the 6GHz channels as (disabled) and I can't scan my 6GHz network.
I'm going to abandon the 6GHz experiment for now.

I tried 6.11.0-061100rc2 with my Comfast 953AX and the kernel crashed. :-(

[morrownr]

I tried 6.11.0-061100rc2 with my Comfast 953AX and the kernel crashed. :-(

Yeah, there is a fix being rushed out for that. The problem was not in the mt7921u driver but I think it was in mac80211. You need to stay on an early kernel until this is cleaned up.