diff --git a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
index d93c3c8..7644ed8 100644
--- a/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
+++ b/demo/src/main/java/ch/dissem/bitmessage/demo/Application.java
@@ -52,7 +52,7 @@ public class Application {
                 .messageRepo(new JdbcMessageRepository(jdbcConfig))
                 .networkHandler(new DefaultNetworkHandler())
                 .security(new BouncySecurity())
-                .port(48444)
+//                .port(48444)
                 .listener(new BitmessageContext.Listener() {
                     @Override
                     public void receive(Plaintext plaintext) {
@@ -109,6 +109,7 @@ public class Application {
             }
         } while (!"e".equals(command));
         LOG.info("Shutting down client");
+        ctx.cleanup();
         ctx.shutdown();
     }
 
diff --git a/domain/src/main/java/ch/dissem/bitmessage/ports/MultiThreadedPOWEngine.java b/domain/src/main/java/ch/dissem/bitmessage/ports/MultiThreadedPOWEngine.java
index 9814c3a..3c4572e 100644
--- a/domain/src/main/java/ch/dissem/bitmessage/ports/MultiThreadedPOWEngine.java
+++ b/domain/src/main/java/ch/dissem/bitmessage/ports/MultiThreadedPOWEngine.java
@@ -43,8 +43,6 @@ public class MultiThreadedPOWEngine implements ProofOfWorkEngine {
         for (int i = 0; i < cores; i++) {
             Worker w = new Worker(workers, (byte) cores, i, initialHash, target);
             workers.add(w);
-        }
-        for (Worker w : workers) {
             w.start();
         }
         for (Worker w : workers) {
diff --git a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
index b6b3c69..69e9e16 100644
--- a/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
+++ b/networking/src/main/java/ch/dissem/bitmessage/networking/DefaultNetworkHandler.java
@@ -48,19 +48,15 @@ import static ch.dissem.bitmessage.utils.DebugUtils.inc;
 public class DefaultNetworkHandler implements NetworkHandler, ContextHolder {
     public final static int NETWORK_MAGIC_NUMBER = 8;
     private final static Logger LOG = LoggerFactory.getLogger(DefaultNetworkHandler.class);
-    private final ExecutorService pool;
     private final List<Connection> connections = new LinkedList<>();
     private InternalContext ctx;
     private ServerSocket serverSocket;
+    private ExecutorService pool;
     private Thread serverThread;
     private Thread connectionManager;
 
     private ConcurrentMap<InventoryVector, Long> requestedObjects = new ConcurrentHashMap<>();
 
-    public DefaultNetworkHandler() {
-        pool = Executors.newCachedThreadPool();
-    }
-
     @Override
     public void setContext(InternalContext context) {
         this.ctx = context;
@@ -82,7 +78,12 @@ public class DefaultNetworkHandler implements NetworkHandler, ContextHolder {
         if (listener == null) {
             throw new IllegalStateException("Listener must be set at start");
         }
+        if (pool != null && !pool.isShutdown()) {
+            throw new IllegalStateException("Network already running - you need to stop first.");
+        }
         try {
+            pool = Executors.newCachedThreadPool();
+            connections.clear();
             serverSocket = new ServerSocket(ctx.getPort());
             serverThread = new Thread(new Runnable() {
                 @Override