Experience with MU-MIMO on OpenWrt

Hardware Questions and Recommendations
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I'm posting this as suggested by @wepee, after a direct reply to the questions in this post asking about the support on MU-MIMO on openWrt.

I don't visit this forum as regularly as I should, so this might be a little late... anyway:

Some time ago, I've played around with a set of 3 TP-Link AD7200 routers , which have 802.11ac wave 2 radios with MU-MIMO capabilities.

I had the 3 routers flashed with OpenWRT LEDE (v17.01).
One of them was configured as an AP, the another two were configured as clients.

I could see the AP advertising MU-MIMO beamformer capabilities (as evidenced by the 'VHT capabilities info' field in Beacon frames, e.g. here).
The clients also showed MU-MIMO beamformee capabilities (e.g., here).
However, my packet captures did not show any MU-MIMO sounding frames or frames containing feedback matrices, which suggests MU-MIMO wasn't being triggered.

I then tried the same experiment, only with the AP flashed with TP-link's stock firmware, leaving the clients running OpenWRT.
In that case, I did see MU-MIMO sounding frames and feedback frames being exchanged back and forth!
I could even see the bandwidth being shared between the 2 clients after MU-MIMO kicked in.

My 'study' was by no means exhaustive - I've only tested one type of hardware - but maybe this suggests that OpenWRT has some issues with MU-MIMO when running in an AP.
I have more details here.

I hope this helps someone!

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This reply is very late... I know. I only discovered it when I was searching on the forum about MU-MIMO.

So in summary, you have 2 units of TP-Link AD7200 routers.
1 is used as an AP and flashed with OpenWrt LEDE; the others are working as clients.
Problem discovered: the MU-MIMO feature was not activated.

Whereas, when AP is flashed back to stock firmware, the MU-MIMO feature is turned on.

@adamiaonr, if you refer to this link: https://openwrt.org/toh/hwdata/tp-link/tp-link_ad7200_talon, it says at the top it is still experimental. So in other words, the firmware is in Alpha version which will have some bugs. Anyway LEDE firmware: https://openwrt.org/releases/17.01/start has already retired (EOL).

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Also this info was provided recently - you can determine from the router with command: