The ServerSocketReceiver and the AbstractServerSocketAppender and their subclasses are using the context's thread pool for client connections which is effectively limiting the amount of possible client connections to a little less than the value of the CoreConstants.MAX_POOL_SIZE which is 32.

In order to allow a flexible configuration of the client connections I recommend introducing a separate thread pool for the ServerSocketReceiver and the AbstractServerSocketAppender (one for each).

The user should be able to configure the core and max pool size to his needs.