Nothing wrong here at all. 

1. Undefined items are either units which have been powered off*, or -- more likely -- where a satellite has connected to the 5GHz radio of a home theatre player. The MAC of the 5GHz radio is +1 with respect to the 2.4GHz radio.
   (*Ghost undefined columns are also a side-effect of the radio -- “WiFi” -- having being disabled on devices.)
2. Blank cells in the matrix body are where there’s no signal. They’re irrelevant. The grey cells are inactive mesh links. The active connections are coloured.  
3. The Beam doesn’t report its ambient noise data in a compatible form. The left column cell is therefore uncoloured. 

Thanks very much for your reply ratty.  I’m reassured there isn’t a problem but I can’t say that I fully understand, would you mind answering some follow up questions please?

1. The +1 Mac Address is the “undefined” speaker and seems to be communicating as it has a green box.  Does this mean it is actually communicating on 5GHz or have I misunderstood your answer; I didn’t think that was possible if it was on SonosNet (which it is as showing on WM0)...I thought that only operated on 2.4GHz?  BTW. It looks to me as if it is the “undefined” beam and playbar talking to its subwoofer in each case while the same speaker properly labelled (ie lounge & pool) is communicating with the left or right dining room speaker.
2. I thought the all the speakers were meant to be able to communicate with each other and then choose the best route at any given time.  Are they blank because there is not a good enough signal between them or are they not even trying to communicate where there is a blank box?  Every example of the matrix I have seen on-line only has blanks where the same speaker intersects on row and column.
3. I understand the answer although it does seem to be a slightly backward step from Sonos….is the information on ambient noise data available anywhere else?
4. An extra question – I had two orange boxes before where the pool room and dining room right speaker were communicating.  When I hard wired the pool room playbar to the network this goes away.  I am assuming this is better because I only have green boxes but I have also read you should only hardwire one Sonos speaker to your network.   This setup would mean both the dining room Left and pool room are hardwired, one directly to a router and the other via an unmanaged switch.  Do you think that will cause any issues…I have included a picture of the updated network matrix with this setup in case that helps?

Apologies if the answers should be obvious to me from your previous reply but I am quite new to this element of the sonos setup and I’m trying to understand how it works so I can get the most reliable arrangement.

PS.  My last post had a comment from the moderator saying personal information should be removed from pictures.  I have assumed this relates to the MAC addresses although I’m not sure as I see various pictures in other posts which contain this information.  Anyway, I have redacted all the MAC addresses on this new picture of the network matrix except the last two digits of the speakers which appear twice.

Thanks again.

Do you actually have any problems? Your matrix looks excellent.

I should point out that, whilst available to users prepared to dig in a URL, the matrix is pretty rough and ready. As Sonos development has progressed it’s acquired a few quirks such as “undefined” headings and a lack of ambient noise data from the latest wireless modules.

HT (home theatre) satellites always communicate via 5GHz with the master player when operating. When the system’s in SonosNet mode they show as WM:0. They don’t participate in the general 2.4GHz mesh but are still active STP nodes (Spanning Tree Protocol -- google it and study to understand how SonosNet determines paths).

The master HT player has two radios: the 2.4GHz one is a general mesh node; the 5GHz one is solely a hub for its satellites.

If two nodes are out of range of one another there’ll be a blank box. There’ll also be blank boxes under the 5GHz devices because they clearly can’t talk directly to the 2.4GHz interfaces. 

Not in any of the user-accessible diagnostic, no. The full diag, which only Sonos can see on submission, would have that kind of data. 

I don’t know where you got the impression that only one Sonos device should be wired. The standard maxim is to wire as many as convenient. The network kit does need to support STP (see above), but most does, either actively or passively. If you had an STP problem in your kit you’d know about it: the network would grind to a halt due to a broadcast storm.

There’s a great explanatory post here; I suggest you have a gander: https://en.community.sonos.com/troubleshooting-228999/sonos-and-the-spanning-tree-protocol-16973

Ratty,

Thank you for your answers and for responding so quickly.  They are really helpful and I think I understand now but I will also have a look at the articles you suggest.  In answer to your question, I was having problems yesterday when we were watching you-tube videos on the TV with the Playbar attached (pool room) and when I grouped to send the music to the rest of the house, the other speakers were juddery, dropping in and out (playbar was still fine).  This made me start googling and trying to understand the network matrix.  At the time my two dining room speakers were showing as red in the left column.  I resolved that problem when I changed the hard wire connection, changed the channel & re-booted everything.  This turned the red boxes to green and it has been fine so far since that, but then I started to try and understand the rest and I couldn’t find any examples which looked like mine….a little knowledge...!

Thanks again.

Red in the left column would almost certainly explain your dropouts, especially if before the additional wire the players were using the SonosNet connection you ringed above. Signal strengths in the low 20s are rather borderline anyway, and ambient noise around the nodes could have been the final straw for a low-delay -- and hence minimally buffered -- grouping with the Playbar. 

There was also the option of fiddling with the Group Audio Delay setting, but depending on the physical arrangement of the rooms you could end up with echo and a loss of lip-sync.