I bought two Aeotec Siren 6 today and I am very happy with them, but only after I fixed the problem I had after I just added them:
When triggering a doorbel or alarm from a flow, the siren often stuttered: it started the Ding Dong sound several times in short succession, until it finally rang normally. Also, when I created a flow that triggers on doorbell 1 to make a timeline notification, I got several notifications. (I do not own a button, so I do not know if it also stutters when you use the button.)
After trying several things, such as including unsecure and healing the mesh (I have plenty z-wave routers) nothing seemed to fix it.
That is - until I saw something peculiar in the settings. All association groups had ID 1 or 1.1 in them - which is Homey. Normally only group 1 (the lifeline) has the controller ID. All the other groups are normally blank when pairing fresh. So I pulled up the manual, which state, as I expected, that all groups 2 - 9 mirror some if the messages that go to the lifeline.
So what happens is: when the bell rings, the Siren sends another bell command though group 4 (Doorbel 1). Essentially this creates a feedback loop, which is kind of a wonder that it ends at all. Group 1 should contain ID 1 (Homey), which always receives all messages. All the other groups should contain ID’s other than 1 or not contain any ID at all.
So when I removed all associations from groups 2 and on, the stutter was gone! I did curiously enough still get multiple timeline messages from the doorbell trigger during the sound, but way less then before.