Sounds like you should have used the “forget existing system” option in the Sonos app before setting up the new one.

But I don’t want to forget the existing system - I still want to be able to use my home system!

You can have the app forget a system and it will show up when you contact it again.

That sounds like a useful workaround, but the actual behaviour I reported is still a bug.  It asked me whether I wanted to add the product to an existing system or create a new system.  I chose the latter so it shouldn’t automatically pick up the Wi-Fi SSID from the existing system.  It should pick the Wi-Fi SSID that you’re currently connected to.

1. Reset the Sonos App, you can then create a brand new system.
2. Return to any/each previous ‘existing’ system and simply connect the App back to it.
3. Move controller/App between the various WiFi networks and App will ‘automatically’ switch and find the system it has previously been connected to.

It works for my various Sonos setups at different locations and the App auto-switches between them all.  You just have to reset the App to create a brand new system for the first time and then simply link it back to any other ‘existing’ systems, as required.

No information is ever lost, because it is all held on the speakers in the various Sonos Households.

So not a bug, this is how the multi-system setup works and is currently ‘by design’ - admittedly though I think it could perhaps be made easier, but the cost of its development to achieve the exact same outcome, would probably not make financial sense. It works quite straightforward, once you understand the necessary steps.

The one thing I dislike about the current process, involving an App reset, is if you customise the layout of the ‘My Sonos’ tab on a controller within a particular Sonos household, the chosen user-layout is forgotten and the App restores the tab to alphabetical order, by category, but it’s a small irritation I can happily live with.

Yes, that’s the bug right there.  You shouldn’t have to reset the Sonos App to install a brand new system.  If Sonos had deliberately designed it so that you have to reset the App first they wouldn’t give you the choice of creating a new system when adding a new product when the app already knows about another system.  The fact that they do let you choose to create a new system, but then mess up the Wi-Fi setting is a bug.  No two ways about it, it’s a bug.  You can argue that it’s not an important bug, but you can’t argue that it’s not a bug.

Personally I think it is a reasonably important bug because it took so long for me to achieve what I wanted and the workaround that people have mentioned here wasn’t obvious to me.

If you have another mobile device available to you of course, then you can use the Sonos App on that other device instead, without having to reset your own controller App - as I said earlier, once you understand the necessary steps, it can be quite straightforward. 

Once a new Sonos Household has been created on the local network subnet, using a separate controller device, you can then go onto connect your own mobile controller to the WiFi network and add the system to your ‘non-reset’ Sonos App, but it does need another controller device to avoid the reset of your own Sonos App. The way things work presently are ‘by design’ it’s certainly not a bug, but as I mentioned earlier, I guess things could be improved, but it would require some development cost to achieve the same/similar outcome. Understanding the necessary steps can usually get you to the same end-point.

So do you work for Sonos and therefore have access to the design and the source code of the app and can say that with 100% certainty?

I’m just a Sonos user, maybe similar to yourself and the App has almost always worked this way, not only for a Sonos S1 system, but also ever since the S2 System was introduced too.

I do use both S1/S2 Sonos systems and have S2 setups at several different locations. I don’t see why you would think it was a bug? If you expect it to work in a different way however, that (IMHO), would more-likely be a ‘feature request’, rather than an existing bug in both S1 and S2 Sonos Households.

You can always check these things however, perhaps when putting forward such a feature request, if you maybe decide to contact Sonos Staff regarding the matter via this (hopefully helpful) support link below:

https://support.sonos.com/s/contact

I did work in the Sonos codebase and can tell you it’s not a bug.

I can understand in daily use it’s good to have the system remember the last used household. It would make it easier for the app to connect to this system. Only when setting up a new household you would actually be hampered a bit by this choice.

It’s perhaps somewhat easier (although not essential) if separate mobile controller devices are used for each Sonos system. Remember that Sonos once produced/sold hardware controllers too, before the mobile device S1/S2 software which, as stated earlier, the App is merely a ‘remote’. or ‘viewer’ of the information/firmware and all settings/services etc; that are held on the players themselves.

Currently where one controller device only is used, the App needs to be reset, or freshly installed, on a compatible mobile device in order to create a brand new Sonos HH. Once any Sonos HH exists though, the Sonos App can connect to it whenever the mobile device is operating on the same network subnet.

When the App has been made aware of multiple Sonos HH’s you can also forget a connected HH in order to connect it to a different one, which perhaps may sometimes exist on the same subnet too.

In my own use-case, my main controllers are an iPad and iPhone XR, I can’t recall the last time the Sonos App on those were ever reset and I do use them both to connect to multiple Sonos HH’s, but whenever I have occasion to perhaps create a new Sonos system, then I just use a reset Sonos App on an iPhone SE (my Wife’s mobile) to do the setup/creation step. Then once the HH is in place, I connect my own controllers to the new HH, so no factory reset is required on my own mobile devices.

Finally, I go back to what I said earlier, once the necessary steps are perhaps understood, it really can be quite straightforward. I’m not personally sure that the Sonos development costs required to change the way things work at the moment would be worthwhile, to achieve what would just be, the exact same outcome.