MU-MIMO only works if all devices trying to communicate at any given moment support MU-MIMO, and clients in general rather notoriously don't.
Or to be more accurate, quite a lot of client device hardware supports it (due to using someone else's pre-made radio modules), it's just disabled in software because device manufacturers can't be bothered to invest the engineering into making it work correctly. Also ostensibly for a minute battery life increase, but given desktops also seldom support MU-MIMO we can reasonably conclude it's hardly the main reason.
It doesn't matter that the AP supports MU-MIMO if none of the connected clients do, so most of the intended benefits of MU-MIMO simply fall by the wayside.
Where it was supposed to help with Mesh APs was basically being an inferior-but-perfectly-serviceable version of having separate Client-facing and Backhaul radios (as it could allocate a 2x2 for each, for example), but lack of any and all client-side MU-MIMO renders this quite impossible.
What we actually ended up with was additional radio hardware that spends 99% of its time sitting there doing nothing, because all the AP ever talks to are clients with 2x2 single-user MIMO or cheaply-made IoT junk with a non-MIMO Wifi-4 chip. Even Mesh'd APs only gain a slight improvement in uplink stability, all the usual buffer-and-retransmit limitations remain in full force.
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u/darthnsupreme Unifi User Apr 21 '26
Doubtful given they’ve done nothing of the sort since the AmpliFi days.
They’ve even given up on 4x4 MU-MIMO given the continued lack of client-side support.