The Sonos app on my Android phone could not connect to the devices - multiple tries, standing right beside each device. Same issue with the app on another Android phone. The phones and other devices in the house had fine Internet access so the Router was not the issue. At each device I pressed the buttons to reboot the device - no improvement. I used a network scanning app on the phone and it said that the 3 Sonos devices were "offline" and not responsive.
Finally I unplugged the Play:5 (the easiest to reach) and plugged it back in. Immediately ALL 3 OF THEM were again online and responsive and the Sonos app could connect to them. The Play:5 self identifies as also being the Controller. When I started the app it wanted to install an update - never clear to me if it is updating the app or updating the devices or both. But I let that complete and everything was normal again.
I would not have been very much out of date since I recall an update like this 3 or so months ago and there was no loss of service before that update. Was there something special in the update to version 9.1 build 45156150?
Best answer by Stanley_4
I have some fairly high end network kit and even without the static/reserved IP v4 addresses being set I rarely saw any churn in the actual assignments from the DHCP pool. Even so following the suggestion made here ended a persistent issue I had with updates causing issues, I was in the beta program at the time and was seeing far more updates than a non-beta user will ever see.
This of course is completely ignoring the IP v6 addresses that suddenly appeared on my LAN as newer Sonos gear (Play 5 Gen2, not ZP-80) started requesting them.
I went as far as setting static/reserved IPs for my controller devices a while back as I was able to correlate glitches in the operation of my system with Sonos controller devices making DHCP requests of my router. This was just a renewal of the existing address, not a change which makes it even more frustrating to me. I got nowhere trying to understand what was going wrong and opted for the "try a fix" versus the "do hours of investigation" route. Got lucky and the oddness stopped and I never went back to investigate further.
I'd love to hear more from Sonos on this issue but so far there hasn't been a lot said about system internals. A easy test would be to do a web-scrape of the remaining available internal Sonos status information a DHCP log capture from your router and a bunch of LAN traffic captures. That might establish correlation but without more internal Sonos access it isn't likely to give causation.
Others have posted stuff about what protocols Sonos uses for communications and how. I don't delve into that unless I have to as I'm not very good at it and only venture there if I can't avoid it.
I'll have to agree with the "something else" diagnosis but I have no clue what it might be. Just as an ancient medicine man could tell you chewing willow bark will help your hangover but without having a clue why, I can safely recommend setting some static addresses and see if it hurts less in the morning. Takes 10 minutes and certainly won't make things worse, so why not.
I'd love to read a post by someone that has the skills and interest to dig into this but so far I haven't seen a lot past the basics.