diff --git a/tests/ft/app/test_mqtt.py b/tests/ft/app/test_mqtt.py
index d186baeb..651afdef 100644
--- a/tests/ft/app/test_mqtt.py
+++ b/tests/ft/app/test_mqtt.py
@@ -384,7 +384,7 @@ class TestMQTT:
         conf = request.getfixturevalue(conf)
         api.node_setting_check(NODE, conf)
         api.node_ctl(NODE, config.NEU_CTL_START)
-        assert 1 == mocker.connected_clients()
+        mocker.assert_client_connected()
 
     @description(
         given="MQTT node and conf_emqx_ssl",
@@ -408,9 +408,9 @@ class TestMQTT:
     def test_mqtt_start_stop(self, request, mocker, conf_base):
         api.node_setting_check(NODE, conf_base)
         api.node_ctl_check(NODE, config.NEU_CTL_STOP)
-        assert 0 == mocker.connected_clients()
+        mocker.assert_client_disconnected()
         api.node_ctl_check(NODE, config.NEU_CTL_START)
-        assert 1 == mocker.connected_clients()
+        mocker.assert_client_connected()
 
     @description(
         given="MQTT node and {conf}",
@@ -498,7 +498,7 @@ class TestMQTT:
     def test_mqtt_cache(self, mocker, conf_cache):
         api.node_setting_check(NODE, conf_cache)
         api.node_ctl(NODE, config.NEU_CTL_START)
-        assert 1 == mocker.connected_clients()
+        mocker.assert_client_connected()
 
         mocker.offline(seconds=1.5)
         ts = (time.time_ns() // 1_000_000) - INTERVAL
@@ -521,7 +521,7 @@ class TestMQTT:
     def test_mqtt_read_bad_req(self, mocker, conf_base):
         api.node_setting_check(NODE, conf_base)
         api.node_ctl(NODE, config.NEU_CTL_START)
-        assert 1 == mocker.connected_clients()
+        mocker.assert_client_connected()
 
         req = {
             "uuid": "bca54fe7-a2b1-43e2-a4b4-1da715d28eab",
@@ -578,7 +578,7 @@ class TestMQTT:
     def test_mqtt_write_bad_req(self, mocker, conf_base, req):
         api.node_setting_check(NODE, conf_base)
         api.node_ctl(NODE, config.NEU_CTL_START)
-        assert 1 == mocker.connected_clients()
+        mocker.assert_client_connected()
 
         req = {
             "uuid": "cd32be1b-c8b1-3257-94af-77f847b1ed3e",
diff --git a/tests/ft/neuron/mqtt/__init__.py b/tests/ft/neuron/mqtt/__init__.py
index 9fdd89ab..862d722e 100644
--- a/tests/ft/neuron/mqtt/__init__.py
+++ b/tests/ft/neuron/mqtt/__init__.py
@@ -60,11 +60,23 @@ class Mock:
         self.broker.start()
         self.client.connect("127.0.0.1")
 
-    def connected_clients(self):
+    def assert_client_disconnected(self):
         """Return number of connected clients to the broker."""
         topic = "$SYS/broker/clients/connected"
         messages = self.get(topic, num=2, timeout=2)
-        return int(messages[-1]) - 1
+        n = int(messages[-1]) - 1  # exclude out client
+        assert n == 0, "there are connected mqtt clients"
+
+    def assert_client_connected(self):
+        """Return number of connected clients to the broker."""
+        topic = "$SYS/broker/clients/connected"
+        n = 0
+        for _ in range(8):
+            messages = self.get(topic, num=2, timeout=1.25)
+            n = int(messages[-1]) - 1  # exclude out client
+            if n != 0:
+                break
+        assert n > 0, "there are no connected mqtt clients"
 
     def get(self, topic, num=1, timeout=1):
         """Get message from the specified topic."""