There are numerous posts here about connecting to Sonos speakers when on a different local network (eg, 192.168.1.0/24 ↔ 192.168.2.0/24). Solutions offered involve opening ports, repeating broadcast traffic across the router, and maybe other steps. There are a few posts offering solutions, but they’re unofficial, disorganized, and often contradictory.
Due to the inherent security issues with IoT devices, it has become standard practice to segment such devices into their own network. Many home routers now have the ability to create multiple networks, and it has become common to see advice for home users to implement this configuration.
The rest of my IoT devices use an an online account which allows communication regardless of network configuration. In my case, Philips Hue, Lutron Caseta, Pentair Screenlogic (pool), August smart lock, Ring doorbell, Ryobi Garage Door Opener, Nest thermostats and smoke detectors, Rain Bird irrigation system, and Amazon Alexa all work just fine across my networks with no configuration, just integration with an online account.
Sonos already provides users with an account, and the data traffic between the controller/app and the speakers should be minimal.
In short, the request is that Sonos implement a system to use the online account to route commands between the controller/app and the speakers so the users can control the system regardless of the network configuration. This would additionally allow for off-site control, which might be of interest to some users.