Has there been a change in the network? Based on the error, my suspicion is that the Sonos is on a different subnet than the PC is on, so perhaps a mesh, or a WiFi extender for one or the other?

Another possibility to add to those mentioned by @Airgetlam, if there have been any changes to the network, is that the computer is seeing the WiFi as a “Public" network, rather than a “Private" network - this would leave the computer unable to see other devices connected to the network as there is increased security applied.

You can find some steps here on how to Make a WiFi network public or private in Windows 10 - if you’re using an Ethernet connection I believe the same steps apply, however you would right click on the Network icon, rather than the WiFi icon,

Thanks for the replies so far.

Xander - you were spot on.  The Win 10 laptop had a property of ‘Public’ for the wireless access point it was connecting to.  I have moved house recently and this is a new access point, but I usually select ‘Private’ during setup - I must had inadvertently hit the wrong option.  I was thrown a bit as the Android and Mac devices are connected to the same access point and Sonos controllers are working fine on both.

Thanks again

Neil