APs are sending Disconnect-Ack without disconnecting clients
So i've run into an interesting issue. We have a guest portal configured on ClearPass, which sends a COA disconnect request on port 3799. Yesterday, we noticed that guests were still locked within the walled garden after authenticating. After looking at a packet capture, the connection looks as expected: Guest signs in, CPPM send disconnect, AP sends disconnect-ACK... but the client is still locked. Reauthenticating manually works, since the client is already registered.
My question is: Why are my APs all of a sudden unable to disconnect clients via COA, and most importantly, why are they sending the disconnect-ACK, when the client is clearly still connected?