After some research:

I can factory reset the play 1 pair, reset the controller on one of my handheld devices, and then add this as a new system. Running on the Bedroom Wifi, using its SSID to connect to it.

That should allow this to be an independent system, WiFi and not Sonos net based.

Will the NAS that serves the existing system be able to serve this one as well?

Yes, as long as it is visible on bedroom’s subnet.

Success! A question - how does one dedicate controllers to each system? Is it just getting each device to connect to it's system and then remembering to not using one device in the vicinity of the other system?

If you reset the controller and then connect it to the system you want it on (temporarily power off the other system if necessary, but it should ask for a button press if it finds two systems) then I don’t think it will give you any option thereafter as long as the desired system is in range.

Please let us know if I’m wrong on that

Although I am not sure I really understand what you are gaining from this…. sorry if I am being slow…..

Why have you disabled some of the radios?

@John B : You are not being slow, it is a long story that’s all.

Chapter 1: In the open space set up of 5 zones, even though all are always in green, I was still having trouble piping uncompressed - because it needs to be in sync - TV audio with the TV/Connect in the same open space, to a group of units in different parts of that space. So I solved that by wiring three Sonos units back to the core network, and because I did not want the unwired two units taking their signals from the wired units, and to force them to connect to only the Boost, i turned off the radios of the wired units. Which worked just fine - and the 5 zone open space is working fine ever since for a few months now. The two unwired units still can't be a stable part of TV audio play, but that is not such a big miss once the three wired ones can be. Music alone in a five zone group continues to be problem free.

Chapter 2 is covered in the opening post. I also have a 1 pair in a remote bedroom that is my only other zone. It always plays in a stand alone manner with a direct and therefore not so strong connection to the Boost. At the same time the room has a very solid WiFi signal thanks to a wired WiFi extender. So I wanted this one zone off Sonos net, and on Wifi, to leverage the more robust WiFi presence. Also, the open space is sometimes silent for a few days running; hence  I wanted to be able to turn off the Boost/NAS/Internet Switch at the mains, but still have the bedroom Sonos play music which is a daily requirement. Which it is doing now, after dividing the 6 zones into two systems; the bedroom Sonos is on very robust Wifi and is a standalone system that works with the Boost powered off, but still works fine with Spotify Connect, for example.

Could I have achieved this any other simpler way? Happy to hear that, if so.

Now the question is how to align two controllers so that they don't operate the system they are not aligned with. That can be done by physically not letting them change rooms, which will work once I remember which is which, but I was wondering if there is a more elegant/robust way of doing this. Are you saying that if I set up a controller with one with the other powered off, it will never work with the latter when it is powered on?

Hi Kumar.  Thanks, I understand the motivation now.   But you talk about two systems.  Do you really have two systems?  Did you factory reset the bedroom speakers and set up as a new system?  

Edit: just re-read and you say this is the case.  Sorry.

On further reflection, I think I have seen posts recently suggesting that with two systems on the same subnet, the controller attachments are not as predictable as they used to be.  It certainly used to be the case that if a reset controller attached itself to a system, it would always attach to that system as long as that system was in range.  If you went out of range of that system, any system within range would offer the chance to connect.  That may have changed, though. 

However, with a different SSID aren’t you OK anyway?  Just ‘forget’ your other SSID on the bedroom controller device?  Not totally sure about this, as everything will still be on the same subnet.

That is what I have done now, but I am not sure it will work, for the same subnet reason. If a device that is not on the SSID that the standalone system is on, the controller it hosts can still connect to it, I think. Time will tell me how to get this bit to work itself out, if that be the case.

I also found a way to get the second system back to the same account at Sonos to which the original one is registered. I don't think this can be done during the factory reset and new add process; at that time one is prevented from entering the same account’s email address as one that already exists.

The remaining inconvenience is that the NAS based playlists can’t be migrated. But that is a small issue, and of course isn't applicable to music service playlists that sit in the cloud.

John B’s recollection is correct: there have been some reports of controllers not connecting to their respective households in a multi-household situation. Standard advice from Sonos is in fact to put the households on different subnets, which can be a nuisance.

Instead of faffing about with two households, needing dedicated controllers, I’d have recommended that @Kumar simply wire a Sonos device in the bedroom as there’s an Ethernet feed to the AE there. If wiring a player is not convenient then simply wire a Boost or Bridge. And if there’s only one Ethernet port on the AE then daisy-chain it through the Boost/Bridge.

For several years, for various reasons, I operated with two Sonos households. At times I had them both on the same subnet, and at times with a secondary router in between to put them on different subnets. Sometimes one was in WiFi mode, sometimes SonosNet mode. Quite a pain really. Since most of the reasons for doing so had evaporated I reset one household and merged it with the other. Pain over.

Out of curiosity, were the yellow / orange cells in the matrix caused by weak signal or interference?  Were you actually having drops or other issues?

I think I might have tried to keep it as a single system (although noted your desire to be able to turn off ‘main’ system).  I don’t really understand why you want to force the main wireless speakers to go back to the Boost when STP might want to go via another speaker.  Or indeed Sonos might want to use direct routing in preference to STP.  Turning wireless back on on the wired units might improve the signal to the main wireless speakers.  Might this in turn improve the SonosNet signal to the bedroom?  It obviously depends on relative positions.  Could you also put a Boost or a speaker in between the main system and bedroom to improve SonosNet signal?

Just thoughts...as I say I understand there are other reasons for seeking greater separation.

I was still typing and thinking while @ratty posted.  I think his suggestion of wiring a Bridge/Boost to the AE is definitely better than my suggestion in at least a couple of ways.  In particular, I think it would allow you to turn off the main system, which my suggestion wouldn’t.

@ratty : The bridge wired to the AEX is with the expectation that the bedroom system then connects to it in place of the boost? Worth a try to see if that does happen,  but for this to work, the boost in the main area would still have to remain powered on?

@John B : The yellow orange cells were caused by the distance from the boost, with the intervening brick wall to be crossed. At the same time, any place that is available for an intermediate bridge doesn't work because the two hops still cost more than the direct connection so the bridge is ignored. And the reason for turning off the radios was to reduce interference as well, with other devices like Firesticks in place. In any case, the wireless speakers in the open space still get a green coloured box to the boost, and before the radios were turned off when one ended up joined to the TV Connect, there still were drop outs in the open space for TV audio. While the bedroom still remained directly connected to the boost. So I turned the radios off, and haven't felt their absence.

Yes.

On a related matter I recall I advised you a while back on how to change the Boost’s STP priority. Correct? This could be important, to ensure the Boost remains the root bridge. 

No.

(And before you worry about the root bridge when the Boost is powered off, the wired Bridge in the bedroom would simply take over under such circumstances.)

Oops; once again I hit best answer instead of like! But it may as well remain there this time.

@ratty : Yes, I have the thing about the Boost remaining root archived, and will pull it out if needed.

This looks like a cool solution, and I have two bridges in a drawer. Will try and report. One question - the speed of the internet via the AEX won’t be affected? It is about 40 mbps.

To the last bit - the Boost and Bridge would trade duties without any interventions as and when the boost is powered on/off?

Correct. If the Boost is present -- and has STP priority set as discussed -- it will be root. It it isn’t then the system looks for the next best candidate, which would be the wired Bridge. When the Boost reappears it takes over again.

@ratty : there is some glitch. All worked well after another factory reset with the boost on, except the bridge that is the same room while shown as secondary node, is still isn't getting picked up by the bedroom zone which remained yellow box connected to the Boost. So I though I will now see what happens if I power down the Boost. Music from the net played for some time and then stopped. And now, the Sonos system in the bedroom is not reachable; the remaining 5 zones+Boost are powered off, of course.

The bridge is daisy chained to AEX; this bit works with no effect on the internet speeds via AEX.

What could be the problem?

Something’s not connecting right. Power the whole system up. Wait 5 mins, screenshot the network matrix and post it.

Are the Boost and Bridge both wired back to a switch?

I will do the power cycle. Both units are wired back to the router ports. The unmanaged switch is for port expansion for the other wired Sonos units.

All green boxes in first column. Bridge is secondary node, nothing connected to it. Play 1 pair in bedroom connected to Boost shown as root bridge, with yellow boxes for signal strength.

Not sure if it is safe to post matrix with mac addresses?

Bridge row is empty white boxes...nothing in them at all. Only the first column is a green box with the OFDM information. No trouble with net speed through it.

Progress, since I have another spare bridge, I swapped it out. Now the bedroom zone is seen as tertiary, connected to it. Should work now.

That can’t be right. There should, at minimum, be some grey boxes showing “blocking”. It sounds like its wireless has failed. Try the other Bridge.

You got there in parallel with my post.