Hi @IanJShaw,

This is a somewhat difficult post to provide an answer for, as every property/Home is different and no one can cater for beams, solid brick-walls, distance to access points, microwaves, fish tanks and anything else that may interfere with a wireless signal.

Anyhow FWIW, just for comparison purposes, here is an outline of my own Home network setup which works well for our three bedroom extended Home here in the U.K.

Firstly, I do have a similar amount of Sonos products (25+) and many other devices connected to the local subnet (approx. 135+ in total, including Hue lighting - usually 35 to 55 devices are in use, on the network, for the majority of an average day) including security cameras, A/V products and some smart-home hubs/devices. 

My own setup is a WiFi 6 AX Sagemcom router, gigabit-wired to three x (distributed) 16 port unmanaged Netgear switches. Two are located front and back of the home on the ground floor and the third switch is centrally located on the upper floor (3 bedrooms/shower room etc.)

Off each of the three switches mentioned, hangs a single WiFi-6AX (wired) mesh hub access point (set in ‘bridged’ AP mode) …then ‘paired’ to each of those mesh hubs are three further WiFi-6AX/WiFi-5AC wired mesh hub access points positioned around the Home to cover any identified weak spots. 

The 2.4Ghz band uses a channel-width of 20Mhz only (highly recommended) - I would personally set the band on each Hub to use the same, non-overlapping, ‘fixed’ channel (1, 6 or 11), but sadly in my case, the mesh WiFi system I’m using from ‘Plume’ does not have that feature available in its software/firmware, so I have to live with auto-channel selection and in fairness to ‘Plume’ it works okay with Sonos, but I think a user-set ‘static’ channel would be a slightly better option.

The 5Ghz band is set to 80MHz width and the Hubs also auto-select their own channels. Again I would personally prefer to set a fixed DFS channel, but the auto-channel-selection is probably (perhaps?) the better option in this instance and it certainly works well.

Anyhow, that wired/wireless LAN setup works fine for Home coverage (including front/rear garden areas) and the wired gigabit LAN/switches for the network-backhaul works really well too with Sonos, which in-turn certainly work best on the (mixed 2.4/5Ghz) WiFi signal rather, than its own internal (wired-mode) SonosNet signal - The Plume mesh WiFi band steering is automatic.

Sonos IP addresses are set static in the routers DHCP reservation table, high up in the subnet. 

I cannot recall the last audio dropout from a Sonos product …and SSDP multicast ‘device discovery’, that the Sonos controllers use to find devices on the subnet, works really well too.

Like everything, it’s not perfect, but certainly works extremely well with Sonos - ISP is Virgin Media and I’m currently using their 1GB/s (download) WiFi connection (100MB/s upload) - but the described setup has previously worked just as well on their 300MB/s and 500MB/s packages too.

Anyhow I hope the network-comparison outlined above, perhaps may go onto assist you with your own network setup.

@Ken_Griffiths 

Thanks so much for your detailed response.

I’m not familiar with either Sage or Plume products.  Would you rate them as particularly highly specced* (i.e. designed for more than the average consumer installation)?  My suspicion is that my Wi-Fi/Router infrastructure, while providing good coverage everywhere to allow devices to access the internet, isn’t handling communication between devices within the house particularly well.

*I realise this isn’t a particularly well defined term!

Thanks again for your response.

The issue with Plume is perhaps their cost as in addition to each hub costing between £150 and £250 (approx.) each, I use 6 of them to provide coverage everywhere, there is also an annual subscription of £100, as most services/security is cloud-based. Security is good, but if their cloud goes offline (rarely happens) then there can be a loss of service. Some people don’t like the idea of a continued subscription. WiFi speedtest is around 400-500MB/s download in most places around the Home.

I maybe would suggest perhaps future-proofing and maybe look at an Asus WiFi 6 AX or 6E mesh systems, using one hub as your main router and bridging any ISP provided router … here’s a nice 6E starter setup, but it’s quite costly, but no yearly subscription…

https://www.amazon.co.uk/ASUS-ZenWiFi-AXE11000-Tri-Band-ET12/dp/B09QRLZMMH

Maybe add a third hub later, if required. I’m waiting for it’s price to come down.

Thanks again Ken

The price of that Asus setup is about four times what I have currently invested in the BT product so maybe that’s an indicator that I need to beef up that part of my home network to give Sonos the support it needs.

The price of keeping ahead of the game can be quite expensive, but prices should come down (hopefully). UK inflation needs to certainly be brought under control too to stop the upward spiral. ‍♂️

I’m thinking of an analogy, it the old days (previous era ) with speakers and amps, if you purchased some nice speakers and new amp, you would probably want to buy some decent speaker cable. The same logic should be applied to large Sonos setup. A 21 device Sonos setup should warrant some investment in network hardware to get the best out of it.

Often, “less is more” with WiFi. A good quality AP in the optimum location (pref ceiling mounted) will perform better than 2 APs in the wrong locations.

That’s been my thinking @craigski .  (And I like the hi-fi analogy).  Unfortunately I’m feeling quite under-qualified to tell where best to invest or what to buy.  I may have a horribly under-performing wi-fi setup in my house but because the only obvious failure points are when Sonos plays up that’s where the finger gets pointed.  Maybe Philips Hue, Chromecast, TP-Link Kasa, the tumble dryer and (for all I know it) the bloody fridge are all suffering in silence but reporting “Good wifi signal”.

Thanks for your comment, it’s helping me decide where to experiment next.

Sonos, by its nature, tests the capabilities of your local network more fully than almost every other device, due to its nature of inter communication between all devices, the local controllers, and reaching outside to various streams.
 

I can’t think of another device that is used that puts as much ‘stress’ on a network. It’s supposed to be not an issue, for a well configured network, but there are just so many poorly configured networks out there that work ‘well enough’ for most things. 

Thank you all for your contributions @Airgetlam @craigski @Ken_Griffiths 

Following your advice and recommendations I replaced the BT Whole Home Wifi mesh with TP-Link Deco XE75 (on special offer so not quite as eye watering as the Asus boxes).

The setup is now a TP-Link Archer Router acting as modem and router (I have some devices connected directly via ethernet), Deco XE75’s in Access Point Mode (thanks for this thread which was SO helpful Troubleshooting Sonos on WiFi | Sonos Community), APs managing their own backhaul via WiFi (but seem to be mostly using the 6E to connect), 21 Sonos players connected over WiFi.

Migrating from one network to another was time consuming but not technically difficult (Turns out doing the same thing over again and expecting different results is exactly what you have to do when it comes to rebooting Sonos players that refuse to give up their connection to the old network).

And I finally have a Sonos system that performs the way I thought it should.

It’s been stable and responsive for two days now so I’m hopeful this isn’t just coincidence.

Thanks again Sonos Community!