There is a new driver called rtw88 for new Realtek based AC chipsets and it's available as a package in OpenWrt. AFAIK, the problem is that current version supports only PCIe radios but... maybe it's worth to try this one (TP-LINK Archer T3U is mentioned as supported and it's based on RTL8812BU): https://github.com/ulli-kroll/rtw88-usb
Thanks a lot. Maybe I would try that if I finally decide to buy what you suggest. Now I am still looking for ONE usb wifi adapter with external antenna whose driver can definitely run properly on openwrt. If I cannot find any one that I am fond of then I would try what you suggest.
I'm testing on the GL-AR750S some RTL8812 and MT7612U USB WiFi dongles that works on OpenWrt v19.07.1 x86, on both, it load the driver but when starts to scan it crash the router at the point it reboots.
On master snapshot r12257,the realtek same that 19.07.1 , it crashes and the MT7612 is working , I tested the Alfa AWUS036ACM and Netgear A6210, STA and AP are working well.
Thank you so much. You literally save my life from the frustration on looking for a usb wifi adapter.
Actually now i am using snapshot 12238. And if you have already tested that A6210 works well on AR750S now I am pretty sure I will buy a Netgear A6210.
Buy the way, i am really fond of the one with usb 3.0. I know that AR750s just has usb 2.0 port. Is it going to happen that if I plug A6210 with usb 3.0 into AR750s, the power of usb 2.0 port on AR750S may not be sufficient for A6120? (Specifically the one with usb 3.0 is NETGEAR A6210-100PES AC1200).
That is my problem, cross compile is really hard. I build already the firmware with the imagebuilder. In the past time, i have build the firmware with the build system. Right know i playing around with cross compile an the sdk image builder...
I recommend this.
It needs unplugging/replugging and restarting ~every week to run it as an AP.
I think the problem is with hostapd or the driver so I'm hopeful it'll get fixed eventually.
I have a Raspberry Pi 4 with a TPLink UE300 ethernet dongle and the Alfa as access point.
I went through many of them and then gave up on Realtek in favour of a Mediatek MT7612U.
Apparently it's really bad code.
I also heard it doesn't work very well on non-X86 hardware so even if you get it to cross compile, it'll probably have bugs.
I don't think the BU is compatible with the AU.
I would have hoped they could reuse code but I think it is too much of a mess.
There are very few USB3 chipset drivers.
I think if you are willing to use 802.11N USB2 then you'll have better luck.
If you want 802.11AC then I recommend the Mediatek MT7612U.
Older I'd go with Atheros.
Newer I went with Mediatek.
In the future, maybe Intel will come out with something USB3, they tend to open source their drivers.