Solved! Go to Solution.
Ok, I solved it myself in the end. Just for people's benefit i've listed the steps to rectify this problem.
1) Switched off all discs
2) Switched on the primary disc (the one connected by ethernet cable to the router) and waited for the solid blue light.
3) Held the reset button for 10 seconds and then allow device to reboot back to a steady blue light
4) On my iPhone, connect to the default SSID now being broadcast by the disc (BT*) using the credentials on the slide out plate on the back of the disc
5) Use the app to add the disc.
6) Power on a second disc and repeat step 3 and 5
7) Power on the third disc and repeat step 3 and 5.
8) Finally, rename the SSID (network name) on the App.
All discs should all be back in sync now with the same SSID.
Hope that helps someone..