A Firmware Update Brought My Roller Shutters Back
Two of our roller shutters simply vanished from my smart home a few months ago. They were no longer recognised, and nothing I tried brought them back.
They are connected through a small USB adapter that talks to the shutters by radio. The fix in the end was not my configuration at all, but a firmware update for that adapter.
Firmware is the software living inside the hardware itself. Updating it is easy to forget, and in this case it was the whole problem.