Hello, not quite enough information. What version of SZ running on your SZ-100, and what model APs are you managing?
What is your "problem", that you think this is releated to please, APs or clients disconnecting or ? Also, where do you see this msg?
I find one Closed bug in our db, SCG-44721: SZ-100: 3.4.0.0.248 Cassandra out-of-service on node2 of 4node cluster.
But that bug is fixed.