Who told you that? 

How are these Sonos devices connected to the extenders? It seems, based on your comments, that these extenders are possibly creating different subnets, making it hard for the two Sonos devices to communicate with each other and sync, although there is also a very remote possibility of a hardware or software failure.

The first thing I’d do is try a simple power down/reboot of both the speakers. Then I’d be looking at the FIOS router (you haven’t told us what it is) to see if the extenders can be forced to be on the same subnet. If none of that works, I would recommend that you submit a system diagnostic and call 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 phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

Thank you - I did a diagnostic and they said I would need a mesh network to bypass the Verizon FIOS router.

Just looking to see which one would work best

Bleh, it’s a bad answer, IMHO. I’d be much more tempted to get a Sonos BOOST and connect that to the router in the closet. Adding a mesh network will likely give you similar problems to what you’re experiencing now.

I’d be willing to bet if you called back in, you’d get a different answer than you did the first time, too. 

Ah…so I plug the Boost into the router and then the boost talks to my two SONOS one?

so confusing.

Just like a mesh router system where you have a main hub and satellites, the Boost connected to the router becomes the ‘hub’ of the Sonosnet mesh network with the speakers as satellites.

Perfect.  will order it!  You were so helpful!