No, it is only possible to pair the Sub Mini with one room at a time.

You would have to switch the Sub Mini between the Arc and Five rooms each time, losing any Trueplay settings you have due to the change of configuration.

Think of it the same way as the Fives being in a stereo pair compared to being used as surrounds. The process is similar with the Sub Mini to switch the room it is paired with.

Nice one, thanks for responding.

How have you found the pairing of the 5s with the sub mini?

I have done this and keeping switching the sub on and off to see if there is a difference. Can only make out a small difference. Thanks. 

I recently purchased a sub mini and paired it with my Play 5. The 5 would play for about a minute and then would become undiscoverable by my system. This has never happened before the 5 was paired with the sub mini. Tonight Sonos tech support told me that it will not pair with a 3 or a 5 or even a connect amp. I wish they had made this clear in the sales material before I purchased the mini. Apparently only the larger sub will work with the 3 and 5 speakers. 

Don’t know who you spoke to, but the information in your post is not correct. See this Sonos Support document: https://support.sonos.com/en-us/article/sonos-products-that-support-sub-mini

Thanks for this article, Ken. Today I started listening to my arc and then added in the 5 (+sub mini) and the system is stable. Then I turned off the arc and the 5 and sub played for 20 seconds and disappeared from the system. Play 5 left (not connected). There is definitely an issue here. Any ideas?

Sorry I have read your post a few times @kcshowman, but can you clarify what you mean exactly where you mention that you turned off the playing ‘group co-ordinator’ (Sonos Arc) ?

Then you mention a "Play:5 left"? (Is that a HT surround, or part of a stereo pair)?

Can you detail the setup a little further please and the precise steps too, as I find your post a little confusing. I’m particularly not understanding the purpose of turning off of the Arc whilst it’s controlling the group.

I’m sorry that my previous post was confusing. I used my iPad with the Sonos app to control my system.  My original speaker that I chose to play back on was the Playbar in my living room (not an Arc). Then I decided to add my dining room speaker (Play5 + sub mini). As I stated, at that point the system was stable and all speakers functioned normally. Then I turned the Playbar off to monitor the Play 5 and sub mini by themselves. Within 30 seconds playback halted and the message on the Sonos app said “Play 5 left (not connected)”. The Play 5 is not part of a stereo pair so I took that to literally mean that the speaker was no longer being seen by the system. It seems that if I start playing in another room and add in the Play 5 and sub mini afterwards they will play properly but they disappear when they are the only zone playing. The tech I spoke to told me that this is a known issue and the sub mini is really only compatible with the Beam, Bookshelf models and smaller speakers like the One. I hope this is clearer.

Where you mention you turned off the playing (group co-ordinator) Playbar - how are you turning it off? - are you powering it off at the power supply, muting it via the App or ungrouping it, or just sliding its volume control to its zero level?

And “Play:5 left” is the name of the speaker?

106rallye, the Play 5 +sub mini is named “Dining room” in my system tab. “Play 5 left (not connected) is the message that appeared on the system tab when communication was lost with it. 
 

Ken, I originally selected the Playbar which is called “living room” in my  system tab. Once the music was playing on the Playbar, I went back on the system tab and touched the icon in the upper right corner of the “Living Room” speaker to bring up the other zones and then selected “Dining Room” to group it with Living Room. After listening to both zones playing together for a couple of minutes, I de-selected Living Room so that I could listen to Dining Room on its own. Then the system lost the Play 5 and displayed the message quoted above.

@kcshowman, 
I think I see what you’re doing now, so you didn’t turn off the Playbar, you just chose to ungroup the Playbar device, which was the playing group-cordinator to allow the Five/Sub to take up the lead and stream the audio instead.

That sounds like a potential network issue to me, or something connected to the origin of the source audio, but can you just try this first as an initial test.

Start the music on the Playbar and then group it with the Five/Sub room ..and then use the group volume control to just mute the Playbar instead, rather than ungrouping it.

So you just press the tiny speaker icon in the volume control as shown in the attached screenshot. Does that work for you?