If the log shows that the client connects, but then gets disconnected after sending a few REQ packets (or at another part of the exchange), the cause is probably that there is an incompability between the version of the server and the version of the client or worker. If the client or worker sends a request that the server can’t understand (if the client/worker uses a part of the protocol that wasn’t defined when the server was compiled), the server will disconnect the client or worker.