Cosy+ devices running a firmware 21.x below 21.2s10 or a firmware 22.x below 22.1s3 use a unique key to encrypt the configuration parameters. This is fixed in version 21.2s10 and 22.1s3, the key is now unique per device.
https://www.hms-networks.com/cyber-security
https://www.ewon.biz/products/cosy/ewon-cosy-wifi
https://blog.syss.com/posts/hacking-a-secure-industrial-remote-access-gateway/