diff --git a/lib/Push.php b/lib/Push.php
index ad9c2a3d..620b1e68 100644
--- a/lib/Push.php
+++ b/lib/Push.php
@@ -30,6 +30,7 @@
 use OCP\Notification\IManager as INotificationManager;
 use OCP\Notification\IncompleteParsedNotificationException;
 use OCP\Notification\INotification;
+use OCP\Security\ISecureRandom;
 use OCP\UserStatus\IManager as IUserStatusManager;
 use OCP\UserStatus\IUserStatus;
 use OCP\Util;
@@ -81,6 +82,7 @@ public function __construct(
 		protected IUserStatusManager $userStatusManager,
 		protected IFactory $l10nFactory,
 		protected ITimeFactory $timeFactory,
+		protected ISecureRandom $random,
 		protected LoggerInterface $log,
 	) {
 		$this->cache = $cacheFactory->createDistributed('pushtokens');
@@ -426,7 +428,11 @@ protected function sendNotificationsToProxies(): void {
 		if ($subscriptionAwareServer === 'https://push-notifications.nextcloud.com') {
 			$subscriptionKey = $this->config->getAppValue('support', 'subscription_key');
 		} else {
-			$subscriptionKey = $this->config->getSystemValueString('instanceid');
+			$subscriptionKey = $this->config->getAppValue(Application::APP_ID, 'push_subscription_key');
+			if ($subscriptionKey === '') {
+				$subscriptionKey = $this->createPushSubscriptionKey();
+				$this->config->setAppValue(Application::APP_ID, 'push_subscription_key', $subscriptionKey);
+			}
 		}
 
 		$client = $this->clientService->newClient();
@@ -733,4 +739,9 @@ protected function deletePushTokenByDeviceIdentifier(string $deviceIdentifier):
 	protected function createFakeUserObject(string $userId): IUser {
 		return new FakeUser($userId);
 	}
+
+	protected function createPushSubscriptionKey(): string {
+		$key = $this->random->generate(25, ISecureRandom::CHAR_ALPHANUMERIC);
+		return implode('-', str_split($key, 5));
+	}
 }
diff --git a/tests/Unit/PushTest.php b/tests/Unit/PushTest.php
index 12f0e84c..6df9870f 100644
--- a/tests/Unit/PushTest.php
+++ b/tests/Unit/PushTest.php
@@ -28,6 +28,7 @@
 use OCP\L10N\IFactory;
 use OCP\Notification\IManager as INotificationManager;
 use OCP\Notification\INotification;
+use OCP\Security\ISecureRandom;
 use OCP\UserStatus\IManager as IUserStatusManager;
 use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Http\Message\ResponseInterface;
@@ -53,6 +54,7 @@ class PushTest extends TestCase {
 	protected IUserStatusManager&MockObject $userStatusManager;
 	protected IFactory&MockObject $l10nFactory;
 	protected ITimeFactory&MockObject $timeFactory;
+	protected ISecureRandom&MockObject $random;
 	protected LoggerInterface&MockObject $logger;
 
 	protected function setUp(): void {
@@ -69,6 +71,7 @@ protected function setUp(): void {
 		$this->userStatusManager = $this->createMock(IUserStatusManager::class);
 		$this->l10nFactory = $this->createMock(IFactory::class);
 		$this->timeFactory = $this->createMock(ITimeFactory::class);
+		$this->random = $this->createMock(ISecureRandom::class);
 		$this->logger = $this->createMock(LoggerInterface::class);
 
 		$this->cacheFactory->method('createDistributed')
@@ -93,6 +96,7 @@ protected function getPush(array $methods = []): Push|MockObject {
 					$this->userStatusManager,
 					$this->l10nFactory,
 					$this->timeFactory,
+					$this->random,
 					$this->logger,
 				])
 				->onlyMethods($methods)
@@ -110,6 +114,7 @@ protected function getPush(array $methods = []): Push|MockObject {
 			$this->userStatusManager,
 			$this->l10nFactory,
 			$this->timeFactory,
+			$this->random,
 			$this->logger,
 		);
 	}