@RobertMEF I'm currently looking to upgrade the wireless access points (ceiling mounted) in my home and am going through the dilema of trying to decide between a 2x2x2 AP and a 4x4x4 AP.  I see a lot of comments online about how great it is to have more spatial streams, but have been wondering if spending more to get more is really worth it, or if more spatial streams is better is more of a marketing gimmick.  I found your comments on this thread enlightening, but would like to pose the question to you, based on my environment. 

Living in a neighborhood of single-family homes, the 2.4GHz and 5GHz bands are fairly congested; the 6GHz band is untouched.

For my network, the maximum number of devices that I would have connected to a single AP at a time is:

     2.4GHz:     20 (mainly light switches, but also includes wireless security cameras streaming to wired NAS)

     5GHz:     5 (includes FireTV cubes, Amazon Echos, tablets, smartphones)

     6GHz:     3 (would include Amazon Echos, tablets, and smartphones)

                Note:  The APs that I'm currently looking at would utilize 6GHz for mesh links.  I will have one AP in my garage that would need to connect via mesh to the AP in an office.  The AP in the office would also need to support 6GHz devices.  If I go with a 2x2x2 AP, would the APs using the 6GHz band for the mesh connection negate the use of this band to support 6GHz clients?

A lot of what I read online indicates that a 4x4 AP can handle multiple 1x1 or 2x2 devices simultaneously with greater bandwidth to each device, so would think that that is better, since I have no clue as to how chatty all of my devices are.  But, I would appreciate your opinion.  Is there any benefit to gain from going 4x4 and would that gain be worth the increased investment?  Note:  I don't need everything to have max bandwidth; I just want everything to have a comfortable 'enough' bandwidth so that it works well.  

Thank you,

Stacy

  @Lee21 

AP to AP connection is the ONLY usecase where 4x4 really shines and brings a benefit. After a lot of testing it is proven that 4x4 MU-MIMO does not work, there is currently no usecase in which it can outperform the old OFDMA. That is purely to the fact, that MU-MIMO must sacrifice QAM symbols in order to work. There is only soo little room for amplitude/phase modulation and either you use it for 4096 QAM + OFDMA or you use it for 512QAM + MU-MIMO. 

4x4 as a backhaul is the only configuration where it truely doubles the performance because as all antennas are in the same spot, you do not need to reduce the QAM symbols to get multiple spatial stream.

So yes, if you really cannot wire up the APs 4x4 is the way to go for you. But you need an entire antenna-block for every AP-AP connection. So for this you should actually go for an AP where you can split the 5 GHZ radio into 2x 4x4, because 5GHz is better for backhaul than 6Ghz just because how much distance it can cover. But you should also consider using directional APs to get more antenna-gain. Remember, every wall halfes the bandwidth of the backhaul. In the best case you could get up 2.5 GBit (in the same room 160Mhz 6GHz), but after one wall its down to 1gbit and after the next wall its like 400mbit or so.

But for your clients it absolutely does not matter, your clients dont put any strain on the WiFi in the first place. You could easily hook up 30 or more FireTVs to a 2x2 AP as the bandwidth is soo low for Video-Streaming, even for 4k.

And it is extensivly tested, that there is no benefit at all for a 4x4 AP compared to a 2x2 AP even for high clients counts. The WiFi standard lacks a lot of what 5G can do. In 5G this is actually working, but the technology of 5G is 10fold better compared to WiFi6 or 7.

  @RobertMEF:  your response / information is, by far, the best I've seen and I really appreciate your taking the time to explain it!  Is it ok with you if I post your comments in other forums?...I'll give you credit.