Hi Guys,
Have been working on my volumio master image today and got it all sorted with kodi and plugins and made a backup using Win32 Disk Imager and have now cloned to two other Rpi 3B and dont get any multiroom showing up ?
Image Version 2.457 on 8Gb Sd Cards
Any ideas on what i need to do to resolve this, i was thinking it might be a service or config file i need to tweak as i suspect because I’ve cloned the cards there is a duplication somewhere.
Simon
I did the same, cloned the SD-Card of my PI#1 and placed it in my PI#2, (same PI hardware, Volumio Rel. 2.444) and changed system name and fix IP für PI#2. Result: Both systems are not shown as multiroom devices.
After that I created a third SD-Card with Volumio Rel. 2.526 from scratch, put it in PI#3 and now I see as multiroom devices: PI#3 and PI#2 OR PI#3 and PI#1, but never ever PI#1 and PI#2 (the cloned one) together.
And after testing a while I found out , that PI#1 is shown in the overview only with the device name of PI#2, but IP and system name are the correct one from PI#1.
Same situation with PI#2, shown with system name of PI#1.
Seems that someting went wrong when copying a SD-Card to create a new Volumio.
Any idea from the experts to solve the issue??
Multiroom requires uniques uuids which are set on first start of volumio.
Therefore the only way to make it work for you would be to delete all user data
I DID IT!!!
Volumio now is multiroomed again.
But I promise that I will never ever reset user data on a customized and running system.
To loose all playlists, total configuration, network connection, NAS definition and additional software like solar panel control, battery charge control and passiv infrared control makes no sense.
I needed more than one day to reconfigure the system. I have my lessons learned now 
But thank you for your help.