Amps

Use the Group menu to have them play together.

Done that they link but no sound from the second unit?

Couple of possibilities, as what ​@Stanley_4 suggests should work. It could be that one or both of them needs a firmware update. Or, there could be wifi interference blocking the signal between the two of them…or, for that matter, a VPN, client isolation on the router, or other such situations. Have you called Sonos Support directly to discuss it?

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 network and Sonos system.

I have done the update firmware is the same there is no VPN active called support no help from them so far😒