Can you clarify what you mean with "cannot talk well ..."?
This setup is what I always use and prefer:

Yes, I don't like a parallel wireless infrastructure in my home, also if it is only on 2.4 GHz.
As already mentioned, no client Isolation and Firewall Rules allow access.
With this setup, none of the speakers should have its own wired connection, when using the Sonos own WLAN network, only one speker should have a wired connection.
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