diff --git a/src/mqtt/MQTT.cpp b/src/mqtt/MQTT.cpp
index c8183cfde..ac022a1ab 100644
--- a/src/mqtt/MQTT.cpp
+++ b/src/mqtt/MQTT.cpp
@@ -651,22 +651,34 @@ bool MQTT::isValidConfig(const meshtastic_ModuleConfig_MQTTConfig &config, MQTTC
 
     if (config.enabled && !config.proxy_to_client_enabled) {
 #if HAS_NETWORKING
-        std::unique_ptr<MQTTClient> clientConnection;
         if (config.tls_enabled) {
-#if MQTT_SUPPORTS_TLS
-            MQTTClientTLS *tlsClient = new MQTTClientTLS;
-            clientConnection.reset(tlsClient);
-            tlsClient->setInsecure();
-#else
+#if !MQTT_SUPPORTS_TLS
             LOG_ERROR("Invalid MQTT config: tls_enabled is not supported on this node");
             return false;
 #endif
-        } else {
-            clientConnection.reset(new MQTTClient);
         }
-        std::unique_ptr<PubSubClient> pubSub(new PubSubClient);
+        // Perform a lightweight TCP connectivity check without using connectPubSub(),
+        // which mutates the module's isConnected state. This only checks if the server
+        // is reachable — it does not establish an MQTT session.
+        // Settings are always saved regardless of the result.
         if (isConnectedToNetwork()) {
-            return connectPubSub(parsed, *pubSub, (client != nullptr) ? *client : *clientConnection);
+            MQTTClient testClient;
+            if (!testClient.connect(parsed.serverAddr.c_str(), parsed.serverPort)) {
+                const char *warning = "Could not reach the MQTT server. Settings will be saved, but please verify the server "
+                                      "address and credentials.";
+                LOG_WARN(warning);
+#if !IS_RUNNING_TESTS
+                meshtastic_ClientNotification *cn = clientNotificationPool.allocZeroed();
+                if (cn) {
+                    cn->level = meshtastic_LogRecord_Level_WARNING;
+                    cn->time = getValidTime(RTCQualityFromNet);
+                    strncpy(cn->message, warning, sizeof(cn->message) - 1);
+                    cn->message[sizeof(cn->message) - 1] = '\0';
+                    service->sendClientNotification(cn);
+                }
+#endif
+            }
+            testClient.stop();
         }
 #else
         const char *warning = "Invalid MQTT config: proxy_to_client_enabled must be enabled on nodes that do not have a network";
diff --git a/test/test_mqtt/MQTT.cpp b/test/test_mqtt/MQTT.cpp
index 4a2eed87d..edf9a3983 100644
--- a/test/test_mqtt/MQTT.cpp
+++ b/test/test_mqtt/MQTT.cpp
@@ -818,16 +818,13 @@ void test_configEmptyIsValid(void)
     TEST_ASSERT_TRUE(MQTT::isValidConfig(config));
 }
 
-// Empty 'enabled' configuration is valid.
+// Empty 'enabled' configuration is valid. A lightweight TCP check may be performed
+// but does not affect the result.
 void test_configEnabledEmptyIsValid(void)
 {
     meshtastic_ModuleConfig_MQTTConfig config = {.enabled = true};
-    MockPubSubServer client;
 
-    TEST_ASSERT_TRUE(MQTTUnitTest::isValidConfig(config, &client));
-    TEST_ASSERT_TRUE(client.connected_);
-    TEST_ASSERT_EQUAL_STRING(default_mqtt_address, client.host_.c_str());
-    TEST_ASSERT_EQUAL(1883, client.port_);
+    TEST_ASSERT_TRUE(MQTT::isValidConfig(config));
 }
 
 // Configuration with the default server is valid.
@@ -846,38 +843,32 @@ void test_configWithDefaultServerAndInvalidPort(void)
     TEST_ASSERT_FALSE(MQTT::isValidConfig(config));
 }
 
-// isValidConfig connects to a custom host and port.
+// Custom host and port is valid. TCP reachability is checked but does not block saving.
 void test_configCustomHostAndPort(void)
 {
     meshtastic_ModuleConfig_MQTTConfig config = {.enabled = true, .address = "server:1234"};
-    MockPubSubServer client;
 
-    TEST_ASSERT_TRUE(MQTTUnitTest::isValidConfig(config, &client));
-    TEST_ASSERT_TRUE(client.connected_);
-    TEST_ASSERT_EQUAL_STRING("server", client.host_.c_str());
-    TEST_ASSERT_EQUAL(1234, client.port_);
+    TEST_ASSERT_TRUE(MQTT::isValidConfig(config));
 }
 
-// isValidConfig returns false if a connection cannot be established.
-void test_configWithConnectionFailure(void)
+// An unreachable server is still a valid config — settings always save.
+// A warning notification is sent in non-test builds, but isValidConfig returns true.
+void test_configWithUnreachableServerIsStillValid(void)
 {
     meshtastic_ModuleConfig_MQTTConfig config = {.enabled = true, .address = "server"};
-    MockPubSubServer client;
-    client.refuseConnection_ = true;
 
-    TEST_ASSERT_FALSE(MQTTUnitTest::isValidConfig(config, &client));
+    TEST_ASSERT_TRUE(MQTT::isValidConfig(config));
 }
 
 // isValidConfig returns true when tls_enabled is supported, or false otherwise.
 void test_configWithTLSEnabled(void)
 {
     meshtastic_ModuleConfig_MQTTConfig config = {.enabled = true, .address = "server", .tls_enabled = true};
-    MockPubSubServer client;
 
 #if MQTT_SUPPORTS_TLS
-    TEST_ASSERT_TRUE(MQTTUnitTest::isValidConfig(config, &client));
+    TEST_ASSERT_TRUE(MQTT::isValidConfig(config));
 #else
-    TEST_ASSERT_FALSE(MQTTUnitTest::isValidConfig(config, &client));
+    TEST_ASSERT_FALSE(MQTT::isValidConfig(config));
 #endif
 }
 
@@ -927,7 +918,7 @@ void setup()
     RUN_TEST(test_configWithDefaultServer);
     RUN_TEST(test_configWithDefaultServerAndInvalidPort);
     RUN_TEST(test_configCustomHostAndPort);
-    RUN_TEST(test_configWithConnectionFailure);
+    RUN_TEST(test_configWithUnreachableServerIsStillValid);
     RUN_TEST(test_configWithTLSEnabled);
     exit(UNITY_END());
 }