I want to smash this system

@Ca.tree.an

There’s not very much information here about the type of wireless network setup, or what channels/channel-widths are in use, or even what WiFi band(s) are in use by each device? Also not clear if each device is streaming its own individual audio source, or if some/all are used ‘grouped’?

What/where are the location(s) of the playing audio source(s), the speed of internet connection (if relevant), or if you’re playing the audio from a local NAS library etc.

What other devices are using the wireless network too, PC’s, phones etc.

I’m also not personally sure such portable ‘Home-Use’ wireless speakers were designed for use in such large numbers in a business-type environment. I would always personally suggest using wired devices in environments where lots of folk maybe moving about the place, as they too might interfere with signals in some cases.

My suggestion however would be to head back to Sonos Support as they can examine your diagnostic reports with the tools they have available and perhaps make some further recommendations, such as using the Roams on non-overlapping 2.4Ghz WiFi channels 1, 6 or 11. …and setting a channel-width of 20Mhz only etc. and placing the router centrally and up high (above head height), or using a ‘wired’ mesh based WiFi setup in ‘bridged’ AP mode,  although it’s also not clear from your post what suggestions the Staff have already provided and what steps you may have already taken.

If they are running on wifi, there may also be other equipment in the spa which, when in use, might cause wifi interference. It’s probably not the best environment to use wireless networked speakers. 

When the system misbehaves is it usually the same speakers involved in the drama? If so, is there something different about their locations relative to the other units -- such as being at one end of your space? (perhaps farther from the router)

Keep a log of events. Are certain times of day more likely to have issues? Are you more likely to experience issues when the spa is full of clients?

Sonos is designed for domestic use.  Larger systems are best run on Sonos’  mesh network, SonosNet - and the Roam is not designed to use SonosNet.  You would have done much better to have either bought Sonos Ones (if you want the same music playing on every speaker), or some cheaper, standalone Bluetooth speakers if not.

A Sonos system of 18 Roams will never work reliably - this is way off the scale of its intended use case, IMO.

When I looked into the system it touted up to 32 speakers on group play. 
 

We have and Eros router with high speed internet, and a few beacons to help spread our wifi. We do have two beacons that are above the rooms. We have two wifi channels one for our computer that plays the speakers and the rest is on a guest channel. 
 

It is always random what speakers go out, and sometimes the one that is closest to the router. We will have no problems for three months at a time and then for one week straight they cut in and out. 

32 is indeed the maximum number of devices that can be added, but that does not mean that it will work in every set up on any network.  And as I said, you have a much greater chance of a large system working flawlessly using SonosNet, which is not available for the Roam.  I stand by my comment that the Roam is a poor choice for your use case.

I am actually surprised that it works well for several months at a time, and that does give room for some hope.

Are ‘beacons’ wireless extenders?  If so, Sonos is not supported for use with wireless extenders.  That doesn’t mean they cannot work, but they can be problematic.  Please would you clarify what exactly these are?

If you haven’t reserved IP addresses in your router for your Sonos devices I recommend doing so - this greatly reduces the possibility of things going wrong when the devices reboot following an update.

These random failures reinforces the probability of network problems rather than Roam faults  

Make sure too that all of the beacons are running on the same wifi channel - 1, 6 or 11 are the best to use. 

Whichever least-used 2.4Ghz non-overlapping WiFi channel you choose to use for the Roams from 1, 6 or 11, also set the channel width to 20Mhz only and ensure the 5Ghz band has a totally different SSID so that they don’t jump onto that band.

Are you within your return period? 

I’m not. I think what’s annoying is I had to call Sonos directly through their business account, so at any point they could have let me know what most of you are saying. That there could have been better options for me, better ways to connect these, or that this was not the right system for what was explained to them. Let alone the amount of times I have been in contact with support within that year where I could have returned them if I knew these did not fit what I needed.