Hi,
did you find any way to restore those session keys situated on Redis? I mean, these must be stored somewhere on one of the SQL databases, or at least some info there that could be used to regenerate the original keys to allow for communication? Maybe salted with a timestamp? (backtracking the time when those devices joined the first time is possible - its in the logs).
It’s really stupid to have devices that are unable to notice a lack of communication with ChirpStack and not try to re-JOIN, but that’s what we have now.