This is more of a nuisance than anything else so I did not formulate it as a question. Periodically, the Sonos app on the iPhone, iPad or PC will be unable to find the Sonos system or will only find some of the devices in it. It is sometimes the case that the iPhone for example finds everything, the iPad finds some devices and the PC finds still a different combination of devices. The system contains a Connect, two Play 1s and a Move. Sonosnet is not in use. Sonosnet did not work well in the environment and appears to suffer from interference from my 4 node Linksys Velop mesh Wi-Fi system. The mesh makes use of the overlapping 2.4 GHz Wi-Fi channels thus stepping on Sonsnet when it tries to use 1, 6 or 11. The Connect is wired via Ethernet and its wireless radio is disabled. Both Play 1s are on Wi-Fi, as is the Move.
From the layer 2 perspective, the MAC address table of every switch in the network contains the MAC addresses of every Sonos device and of all devices running the Sonos app. The switches are all Cisco managed switches. While this problem is occurring, the MAC address tables of all switches retain the MAC information so this eliminates the possibility that the issue is due to switches losing MAC info for some devices.
From the layer 3 perspective, the Wi-Fi connected Sonos devices, the wired Sonos device, the smartphones, tablet & PC with the Sonos app that are having the issue with finding the Sonos system are on all on VLAN 1. The PC is wired via Ethernet. I have reserved the IPs for all Sonos devices in DHCP. While this problem is occurring, all Sonos devices & all devices running the Sonos app are fully pingable with sub-4ms ping times.
Many other systems that use an app on the same mobile devices, wired & Wi-Fi network & VLAN to reach their devices never have discovery issues. 9 Reolink cameras, a pool cleaner, a Simplisafe alarm system, a MyQ garage and gate opener, a Ring video doorbell with 5 Chimes, 4 Brilliance Smart outlets, 2 Govee thermometers, a Lutron Caseta system, 7 Amazon Dots, 2 Ecobee thermostats, and a sprinkler controller all with their own mobile apps all work, all of the time, and do not have issues with being unable to find their respective system components. This is clearly a Sonos-only issue on a stable, monitored and well maintained network. It is also a very small and simple Sonos implementation, having only 4 Sonos devices. It is also the case that once the app can see all Sonos devices, it readily plays music to all of them for hours at a time, until we use the app to turn off the music. It doesn’t lose track of the system once it finds it.
Another puzzling aspect is that if it is just allowed to sit, without restarting anything, the devices will eventually show up. That is not helpful when you are ready to turn the music on and there is no system found. Very often the app can be Reset, then told to join an existing Sonos system and it finds everything it could not find prior to the Reset. As a former software developer, I see at least one change Sonos could easily make. Before telling the user their Sonos system cannot be found, the app could internally perform the same Reset step, and then tell the app to join the existing system. If it cannot find the Sonos system after that is tried, then it can say it has a problem. It seems odd that if a Reset often resolves this, that the app is not written to try that before alerting and frustrating the user. Because many other products, using various networking protocols and standards, readily find all of their devices on the same network, when the Sonos app cannot, they really need to examine what they are using as a discovery method, because it is either flawed or not robust enough.
Comments from others experiencing this behavior would be welcome and hopefully Sonos will look into what should be a simple thing to resolve.