Not sure how to resolve your issue, but I think it would be worth a drive to Best Buy on veterans in Metairie and talk to the Magnolia dept as they know a pretty good amount. 

Wiring a single Sonos device puts all Sonos devices on SonosNet, and not your own Wi-Fi signal. Due to the way many mesh networks operate, creating multiple subnets, which are confusing to the way Sonos works, the ideal way is to wire one (or more) Sonos device to the DHCP device, which has traditionally been the base / router device of the network.

The folks at eero are generally correct, you should not be wiring a Sonos device to extra pucks. 

Your setup, based on your post, seems essentially correct, a Sonos device connected to your root device. If you’re experiencing dropouts, there are likely other issues of wifi interference going on. Make sure, for instance, that your error network broadcast channel isn’t the same one as Sonos. Channels 1, 6 and 11 are the ones that don’t overlap, and you can choose one of them for your SonosNet channel in the controller, then go in to your euro network and make sure it is using another. Make sure (and I’m going back to all the potential solutions in the FAQ I have linked) that you don’t have other network devices or potential electrical other sources of interference near your speakers. I’ve had trouble in the past with a microwave that was ‘leaking’ enough RF to cause difficulty. 

Also, be aware that not all sources of interference are from within. I’ve had neighbors who set up a new Wi-Fi router that stomped all over the SonosNet channel I was using. If you keep running in to issues, try swapping channels around.

The extra eero pucks are great for other devices, such as phones, or tablets, or PCs, they just aren’t serving with Sonos.

Edit: cleaned up a lot of autocorrect nonsense with the word eero.

Thank you for the reply. (I have performed a number of troubleshooting steps)

1. Are you saying by the following statement:

   “The folks at eero are generally correct, you should not be wiring a Sonos device to extra pucks.” 

That it is “not” unique to Eeros’ line of pucks?  Thereby I shouldn’t physically connect “any” brand of mesh pucks to the speakers (beyond the main router)?    (Which sonos tells me “to do”).

2. Do you think dropping my wired Sonos Boost and going to a wireless setup may be a good idea since the wired setup is forcing all of the (12) sonos one speakers to work off of the puck that is being used as the router?  (hoping that the speakers will all start conncecting to the pucks closer to them).  On one hand it makes sense to me so that the multiple pucks “share” the load, but on the other hand Sonos says to use a boost when going beyond 5 Sonos devices.  

      3. Should I consider abandoning the Mesh system and purchase a more “robust” router? (I am not                even sure if that is a “real’ option.   

thanks again, I am determined to remedy this

PS: just as a reminder, it is only Spotify that gives me such grief

1. It depends on the way that particular brand of “mesh” devices work. Some would need to have the SonosNet be the primary connection method, due to the way they work, others might not. It boils down to whether the mesh devices broadcast. It isn’t enough to have the same SSID and password, all Sonos devices, due to the nature of the communication amongst themselves, require the same subnet. 
2. I think you’d be fine. It’s only in the last couple of months that I’ve even heard them talk about the need for multiple BOOSTS or connection points to the router. I’ve run 20 plus speakers off of a single connection to a BOOST without issue before, and am now running a single connection to an Arc, having retired my BOOST due to proximity. However, there’s absolutely nothing wrong with providing the Sonos multiple points of connection to the router directly. SonosNet does work as it’s own mesh, so each speaker would help “boost” the signal to others, whether they’re being “played” or not.
3. Hard to tell, honestly. I think if you just move your Sonos to SonosNet connection, you’d likely be happy. The issue is that each streaming service has different “sensitivities” to disconnects, and in your case, it seems like Spotify is the most sensitive. There’s also the potential issue that we’ve not discussed that the concern is Spotify’s servers, and not your local connection, too. I think I’ve read that in the last 48 hours or so, there was an issue with the Spotify servers...but not being a subscriber, I’ve not paid too much attention to that. 

Unspoken, but may be useful to your mental cache of data is the fact that many / most streamers use a completely different server to provide the stream to your Sonos speakers. So if you use their app on your phone, you’re likely connecting to a different server than if you connect using your Sonos. 

I think @Airgetlam is right on all counts. You should forget about 'overloading' a Boost or the primary puck. They are perfectly capable of handling that.

Leave the Boost wired. Allow other devices to connect to SonosNet. I think the Eero folks are completely wrong to suggest operating Sonos in wireless mode. 

I would give the same advice for every mesh system. For that matter I I would advise most people with a conventional wifi to wire one Sonos device.

Do you own a Roam or a Move?  If not you should remove all WiFi credentials from the Sonos system.

I assume wireless on your original router is disabled?

Hard not to like a post where someone says I’m right on all counts :)

And, to be honest, I agree with all of John’s statements as well.