Perhaps see the instructions in this Sonos Support Article:

https://support.sonos.com/s/article/1061

Note that some WiFi networks at Holiday rentals can occasionally be problematic as they sometimes have a login page process to setup a device (such as a mobile/tablet) on the wireless network and those pages can/do cause problems for Sonos products and prevent them joining the network, so in that case you might have to consider using your own router/access point connected to the network as a ‘middle-man’ device, or perhaps use a mobile WiFi hotspot instead - so I would keep that in mind.

The fallback, if all else fails, is to use the Roams Bluetooth connection to your mobile.

HTH

You must have the Sonos app on your device to place them on the network that is the only way you can see the speakers. Conversely, that is the only way to create a stereo pair. Once removed from a network the stereo pair is broken. Also you cannot create a stereo pair over bluetooth.

Thank you AJ & Ken. Perfect advice. 

If you use a simple “travel router” which is set to mimic your home wifi SSID and password (i.e. the network the “REAL” sonos system is on) this should work fine… Just connect the travel router to the vacation rental router via ethernet and fire up. Make sure your phone is connected to the travel router. You might also have to re-pair the roams.