Your TotoLink X5000R uses the mt7915 chipset for its wifi radio (and i think in dbdc mode, which makes it a 2t2r device)
Searching in mt76 repository for "MU-MIMO" yielded following results: https://github.com/openwrt/mt76/search?q=mu-mimo&type=commits
- MU-MIMO support (Downlink and Uplink) was added for mt7915 in June 2020
- Uplink Mu-MIMO (UL MU-MIMO) was disabled Septemer 2020
- UL MU-MIMO was enabled for mt7915 in October 2021
- UL MU-MIMO was again disabled for mt7915 in June 2022
Why was it disabled? - The commit message reads:
After initially establishing a connection, it can produce multi-second latency
spikes and tx hangs when pushing traffic.
It should work better for MT7916 and MT7986, so leave it enabled there
As you can see it indeed depends on your chipset, if MU-MIMO is enabled or not. Furthermore, MU-MIMO is not automatically the same as beamforming. According to Wikipedia, classical MU-MIMO does not make use of beamforming technology, whereas CO-MIMO does [source 1]. To me it is not clear if this is a difference in name only, or if there are actual technical differences between the two.
What we know for sure is that beamforming can and is enabled and disabled in OpenWrt for various chipsets separately, as we can see here: https://github.com/openwrt/mt76/search?q=beamforming&type=commits
Initial beamforming support was added for mt7915 with following commit: https://github.com/openwrt/mt76/commit/6377b7f330be4a633f6effa6a232f46ad1234647.
You can also check your config if beamformer and beamformee are enabled, like this: cat /etc/config/wireless
Look for
option he_su_beamformee '1'option he_su_beamformer '1'option he_mu_beamformee '1'
Source: source 2
PS: Source 2 recommends to set your devices BSS coloring to "8", which is only partly correct. As far as I understand it, BSS should be different for every active connection. So if you have two SSIDs, these two should have different numbers, so as to avoid interference. Do not set BSS coloring to 8 on all your devices. If you refrain from setting it, it will be automatically set to a random number between 1 and 64 (or is it 128?) or something. This info is mentioned in one of the comments down below in that thread.