Hi, The 3 fan lights and the 1 normal light which are connected to this unit are all ON and cannot be switched off. I started Toolkit and scanned the network and it does not show up. All other units show up on a rescan/scan. These were installed over 20 years ago. There are 2 of these and 3 x 5104D750 Plus newer DIN rail units which were added later for other parts of the house. I gather that you cannot purchase these any more so was wondering how easy it would be to replace it with a DIN unit such as a 5504RVF
