Java TCP/IP Server will not pass on the output to clients

This is part off a bigger application, that is why the send methods uses String-Arrays, which are generated by another pieve of Software. This worked before. This piece is code is designed to accept one client connection at a time on the specified port and send Data to them. FOr some reason the data written to out will never be seen by the clients, i even tried printwriter, ArrayOutputstream and many more. At this point i have no idea on what is wrong here. I have wasted several hours on debugging and rewritting without any success. I tried making clients with simple echo, reading line-by-line etc. But no matter what i do, they never see any output. I Would really appreciate your suggestions.

The while(true) loop was added for testing purposes

 import java.io.BufferedOutputStream;
    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.IOException;
    import java.io.InputStreamReader;
    import java.net.ServerSocket;
    import java.net.Socket;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    public class ServerStream implements Runnable {
        private ServerSocket serverSocket;
        private Socket socket;
        private volatile boolean cancel = false;
        private int port = 0;
        final static Logger logger = LoggerFactory.getLogger("odc");
        private BufferedOutputStream out;
    
        public ServerStream(ServerSocket serverSocket) {
            this.serverSocket = serverSocket;
            this.port = serverSocket.getLocalPort();
        }
    
        @Override public void run() {
            logger.info("Opening Serversocket at port {}", port);
            try {
                while (!cancel) {
                    if (this.socket != null && !this.socket.isClosed()) {
                        socket.setKeepAlive(true);
                    }
                    socket = serverSocket.accept();
                    logger.info("Client connected to Serversocket! at {}", port);
                    out = new BufferedOutputStream(socket.getOutputStream());
                    String[] a = new String[1];
                    a[0] = "AAAAAAAA";
                    while (true) {
                        send(a);
                        Thread.sleep(100);
                    }
                }
            } catch (Exception e) {
                logger.error(e.getLocalizedMessage(), e);
                e.printStackTrace();
            }
        }
    
        public boolean isConnected() {
            return socket.isConnected();
        }
    
        public void send(String[] arg) {
            StringBuilder builder = new StringBuilder();
            for (int i = 0; i < arg.length; i++) {
                builder.append(arg[i]);
            }
            try {
                out = new BufferedOutputStream(socket.getOutputStream());
                out.write(builder.toString().getBytes());
                out.flush();
                System.out.println(builder.toString());
            } catch (Exception e) {
                e.printStackTrace();
                logger.error(e.getLocalizedMessage(), e);
            }
        }
        public void cancel() {
            cancel = true;
            try {
                serverSocket.close();
                if (socket != null) {
                    out.flush();
                    out.close();
                    socket.close();
                }
    
            } catch (IOException e) {
                logger.error(e.getLocalizedMessage(), e);
            }
        }
        public int getPort() {
            return port;`enter code here`
        }
        public void setPort(int por`enter code here`t) {
            this.port = port;
        }
    }