Lost surround and sub ( after update ?)

So this is where I am thinking about this.

Sorry its a little long, but please read as I want to make sure my thinking and testing approach is reasonable. 

I am closer to thinking (although not ruling out 100%) this is possibly not a network issue in terms of our home mesh/router network, but there is something still to explore in the ad-hoc network that Sonos sets up and maintains as part of Home Theatre connectivity. Logic would suggest that global failure of routers/home networks or the global introduction of interference is unlikely to occur simultaneously in April. Probability is that this is change related somewhere in the eco-system and having a direct or indirect trigger of the issue. 

I think we need to do a few things if we are going to understand this more. (Happy to get some feedback to make sure we all agree on the approach before we head off down a path). 

1. Firstly, 2 people, thus far, have confirmed that the Operating Channel has changed at some point during a sound drop out. I think we need to have more people who are affected with the issue monitor their Operating Channel and ARC packet loss when the system is working, and then check if the Operating Channel has changed as soon as sounds has dropped or impacted. This will start to focus in on whether HT ad-hoc network channel changes are related (or at least present) during the issue and if packet loss features. 
2. Secondly, we need to have people who are not effected by the sound issue, monitor their Operating Channel and packet loss and see if they experience changes of the frequency. i.e. does it remain solid on one channel, or does it change BUT still work despite that frequency change. 
3. Thirdly, we should record the ad-hoc channel it was operating on + ARC Packet Loss when it was working, and then when it was not working (or changed and remains working) and post here for some visibility and analysis. i.e. I note that the channel myself and Peter got changed to was a DFS channel. Might be nothing, but data is always helpful to rule in or out. 

The above two items should enable us to triangulate a little on what @Ken_Griffiths originally advised we should monitor and get to understand if this is part of the problem or not. Both him and @ratty seems to have a good understanding of the Sonos Network side so it would be great to get their feedback and experience based on our data.

If we can prove correlation between the ad-hoc HT channel movement and the sound issue, but we are not experiencing any other networking issues on our broader network, then we have something to ask Sonos about in terms of the ad-hoc channel behaviour and why this could be occurring. We may also find a correlation between high packet drops on the ARC, and then a channel change. 

Stuff to think about (Brads mad ramblings)

• There are users on this forum that have been rock solid for months.  Some have had the issue (like Peter) on their rock-solid systems after nearly two months. So it is plausible that this can occur after some time, or maybe never at all. Therefore, I think it's the ‘trigger point’ that we really don't understand. yet. i.e. why some people get it in 5 mins, why some people are running for hours/days/month before the issue and why some people have not had the issue. Everything we need to do is better understand that trigger point as much as possible - and that does require quite a bit of effort and discipline! 
• In terms of the trigger point, I am not convinced its just Apple TV. Some people don't use Apple TV and have experienced the issue. It could be Apple TV is used more and exasperates the issue more, but we must remember that Apple TV does not correlate to all issues of sound drop-outs.
• In terms of packet loss, I think we need to compare this with people who having a working and solid HT setup. I suspect that packet loss will be there as well but we need that comparison to rule in/out whether it's an issue. I do agree that drops are not good, but drops should more than likely cause choppy sound rather than no sound at all. Unless packet loss is a trigger for Sonos to change the ad-hoc 5Ghz channel and thus the problem. We should also remember that some people have moved from Standard Wi-Fi, to Wired and to fully Ethernet connected on all speakers and still get the problem. That does not mean its NOT a network issue, as whether wired or wireless, there is still networking protocols and transit to consider within the Sonos eco-system. 

Where is Brads head right now?

My personal thoughts at this stage (and I probably should not solution-ise, but just for transparency) is that the issue triggers at random times and is not consistent. i.e. its not always “move from Disney to Netflix and the problem is 100% triggered at that point’. So we are dealing with a level of randomness before the issue occurs. Moving HT ad-hoc channels due to interference, packet loss triggering a channel change etc are all possible trigger points which are likely to occur at random times rather than be consistent. i.e. a packet loss trigger to move channels would occur based on the amount of data pushed through the ARC before it decides to move, and interference is random by definition and based on what is occurring in the network at that time.

So my head is a little fuzzy to be honest. But when I think about randomness I do think about things like packet loss and network changes or interference as they are not the same as a specific bug which is triggered when the code goes through a routine and hits that line of code with a bug - that would be pretty consistent to replicate in my mind. 

What does everyone think? Its a long post, but it might be good to digest my thoughts and think about whether we need to adopt or change the approach. To be honest, I am all ears for any suggestions and thoughts.