diff --git a/lib/tunnelbroker/peer-to-peer-context.js b/lib/tunnelbroker/peer-to-peer-context.js
--- a/lib/tunnelbroker/peer-to-peer-context.js
+++ b/lib/tunnelbroker/peer-to-peer-context.js
@@ -194,7 +194,9 @@
   );
 
   await Promise.all(devicePromises);
-  return Object.keys(sentMessagesMap);
+  // Returning messageIDs of failed messages.
+  const sentMessages = new Set(Object.keys(sentMessagesMap));
+  return messageIDs?.filter(id => !sentMessages.has(id)) ?? [];
 }
 
 const AUTOMATIC_RETRY_FREQUENCY = 30 * 1000;