Advanced Wireless Settings - odd default choices

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gr8sho wrote:

.......... The second was for MU-MIMO support, which Apple recommends for its devices.  Oddly this feature is apparently off by default.  Can someone explain this choice to me?  I'm going to switch this on along with the other two options on offer unless someone has strong recommendation against.  Generally I'm in favor of keeping devices like this in as close to factory default state as possible.

 

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Regarding MU-MIMO settings:
MU-MIMO (Multi-User MIMO) should not be mixed with MIMO. MIMO is actived always in Orbi. Orbi has 2x2 design and can support up to 2 spatial streams.So using MIMO Orbi can transmit and receive data streams to/from capable devices using two antennas and thus achieve higher throughput.
Most mobile phones support max of 2x2 spatial. Latest iPhone XS supports only 2x2 spatial streams. 
MU-MIMO is something totally different! MU-MIMO uses a special form of beamforming (on 5 GHz band only) to enable multiple devices to share the same Wi-Fi airtime, so you need at least two MU-MIMO devices to get any benefit from MU-MIMO.
Important to note is that -practically- many 4x4 based designs support only up to three simultaneous devices, 3x3 designs support up to two, 2x2 designs (e.g. Orbi) can't support any in most cases! Orbi has capability to provide peak throughput gain with two single-stream devices for few device types that have “correct” chipset.
In fact, for most cases with most of available devices, MU-MIMO provides no significant benefit. And in other cases, it can result in degraded Wi-Fi throughput! That's why it's disabled by default in Orbi as well as in most of other wifi router manufacturers.
So in summary the MU-MIMO in a router is like 3D in a TV, isn't costing us extra anymore but certainly not always adding a value or a reason to prefer one product over another.