So, is it just a router, or a mesh network?

Are you certain your phone is connected to your new router?

Is there a chance that your phone is connecting to the 5Ghz side, and the router is not passing the data between the 5Ghz and 2.4Ghz sides inside the router?

I guess the other question is how sure are you that your Sonos is connected to the new router? Are you able to use a different controller to operate them, and it is just your phone?

Might be worth reviewing this link as well.