diff --git a/bundles/org.openhab.binding.gardena/src/main/java/org/openhab/binding/gardena/internal/GardenaSmartWebSocket.java b/bundles/org.openhab.binding.gardena/src/main/java/org/openhab/binding/gardena/internal/GardenaSmartWebSocket.java
index 5b339248e4f..1e26b1a4d6c 100644
--- a/bundles/org.openhab.binding.gardena/src/main/java/org/openhab/binding/gardena/internal/GardenaSmartWebSocket.java
+++ b/bundles/org.openhab.binding.gardena/src/main/java/org/openhab/binding/gardena/internal/GardenaSmartWebSocket.java
@@ -16,7 +16,6 @@ import java.io.IOException;
 import java.net.URI;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
-import java.time.Instant;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
@@ -49,12 +48,12 @@ import org.slf4j.LoggerFactory;
 public class GardenaSmartWebSocket {
     private final Logger logger = LoggerFactory.getLogger(GardenaSmartWebSocket.class);
     private final GardenaSmartWebSocketListener socketEventListener;
-    private final long WEBSOCKET_IDLE_TIMEOUT = 300;
+    private final int MAX_UNANSWERED_PINGS = 5;
 
     private WebSocketSession session;
     private WebSocketClient webSocketClient;
     private boolean closing;
-    private Instant lastPong = Instant.now();
+    private int unansweredPings = 0;
     private ScheduledExecutorService scheduler;
     private @Nullable ScheduledFuture<?> connectionTracker;
     private ByteBuffer pingPayload = ByteBuffer.wrap("ping".getBytes(StandardCharsets.UTF_8));
@@ -115,8 +114,9 @@ public class GardenaSmartWebSocket {
     }
 
     @OnWebSocketConnect
-    public void onConnect(Session session) {
+    public synchronized void onConnect(Session session) {
         closing = false;
+        unansweredPings = 0;
         logger.debug("Connected to Gardena Webservice ({})", socketId);
 
         ScheduledFuture<?> connectionTracker = this.connectionTracker;
@@ -129,9 +129,9 @@ public class GardenaSmartWebSocket {
     }
 
     @OnWebSocketFrame
-    public void onFrame(Frame pong) {
+    public synchronized void onFrame(Frame pong) {
         if (pong instanceof PongFrame) {
-            lastPong = Instant.now();
+            unansweredPings = 0;
             logger.trace("Pong received ({})", socketId);
         }
     }
@@ -170,14 +170,14 @@ public class GardenaSmartWebSocket {
      */
     private synchronized void sendKeepAlivePing() {
         final PostOAuth2Response accessToken = token;
-        if ((Instant.now().getEpochSecond() - lastPong.getEpochSecond() > WEBSOCKET_IDLE_TIMEOUT) || accessToken == null
-                || accessToken.isAccessTokenExpired()) {
+        if (unansweredPings > MAX_UNANSWERED_PINGS || accessToken == null || accessToken.isAccessTokenExpired()) {
             session.close(1000, "Timeout manually closing dead connection (" + socketId + ")");
         } else {
             if (session.isOpen()) {
                 try {
                     logger.trace("Sending ping ({})", socketId);
                     session.getRemote().sendPing(pingPayload);
+                    ++unansweredPings;
                 } catch (IOException ex) {
                     logger.debug("Error while sending ping: {}", ex.getMessage());
                 }