A few questions:
1/ Do you have a Mesh network?
2/ Please look at my article:
This is not the solution for my setup.
I have a mesh network but my IP addresses are allocated for each device Mac address.
The latest app worked fine for many years while this new app has big problems on the speakers.
Not all mesh networks are the same. Some, depending on their setup, break their networks into different subnets, something that Sonos doesn’t deal with well. Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it?
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.