diff --git a/src/config/settings.h b/src/config/settings.h
index ea864ede..ebb78586 100644
--- a/src/config/settings.h
+++ b/src/config/settings.h
@@ -68,11 +68,11 @@ typedef struct {
 } cfgLed_t;
 
 typedef struct {
-    char broker[MQTT_ADDR_LEN];
+    String broker;
     uint16_t port;
-    char user[MQTT_USER_LEN];
+    String user;
     char pwd[MQTT_PWD_LEN];
-    char topic[MQTT_TOPIC_LEN];
+    String topic;
 } cfgMqtt_t;
 
 typedef struct {
@@ -272,10 +272,10 @@ class settings {
             mCfg.serial.debug    = false;
 
             mCfg.mqtt.port = DEF_MQTT_PORT;
-            snprintf(mCfg.mqtt.broker, MQTT_ADDR_LEN,  "%s", DEF_MQTT_BROKER);
-            snprintf(mCfg.mqtt.user,   MQTT_USER_LEN,  "%s", DEF_MQTT_USER);
+            mCfg.mqtt.broker = DEF_MQTT_BROKER;
+            mCfg.mqtt.user = DEF_MQTT_USER;
             snprintf(mCfg.mqtt.pwd,    MQTT_PWD_LEN,   "%s", DEF_MQTT_PWD);
-            snprintf(mCfg.mqtt.topic,  MQTT_TOPIC_LEN, "%s", DEF_MQTT_TOPIC);
+            mCfg.mqtt.topic = DEF_MQTT_TOPIC;
 
             mCfg.led.led0 = DEF_LED0_PIN;
             mCfg.led.led1 = DEF_LED1_PIN;
@@ -366,10 +366,10 @@ class settings {
                 obj[F("topic")]  = mCfg.mqtt.topic;
             } else {
                 mCfg.mqtt.port = obj[F("port")];
-                snprintf(mCfg.mqtt.broker, MQTT_ADDR_LEN,  "%s", obj[F("broker")].as<const char*>());
-                snprintf(mCfg.mqtt.user,   MQTT_USER_LEN,  "%s", obj[F("user")].as<const char*>());
+                mCfg.mqtt.broker = obj[F("broker")].as<const char*>();
+                mCfg.mqtt.user = obj[F("user")].as<const char*>();
                 snprintf(mCfg.mqtt.pwd,    MQTT_PWD_LEN,   "%s", obj[F("pwd")].as<const char*>());
-                snprintf(mCfg.mqtt.topic,  MQTT_TOPIC_LEN, "%s", obj[F("topic")].as<const char*>());
+                mCfg.mqtt.topic = obj[F("topic")].as<const char*>();
             }
         }
 
diff --git a/src/defines.h b/src/defines.h
index 1c2e5d23..62c61a9f 100644
--- a/src/defines.h
+++ b/src/defines.h
@@ -85,10 +85,7 @@ union serial_u {
 #define DEVNAME_LEN             16
 #define NTP_ADDR_LEN            32 // DNS Name
 
-#define MQTT_ADDR_LEN           32 // DNS Name
-#define MQTT_USER_LEN           16
-#define MQTT_PWD_LEN            32
-#define MQTT_TOPIC_LEN          64
+#define MQTT_PWD_LEN            64
 
 #define MQTT_MAX_PACKET_SIZE    384
 
diff --git a/src/publisher/pubMqtt.h b/src/publisher/pubMqtt.h
index f3ff4eb1..895d9398 100644
--- a/src/publisher/pubMqtt.h
+++ b/src/publisher/pubMqtt.h
@@ -44,7 +44,7 @@ class PubMqtt {
             mSunrise        = sunrise;
             mSunset         = sunset;
 
-            mClient->setServer(mCfg_mqtt->broker, mCfg_mqtt->port);
+            mClient->setServer(mCfg_mqtt->broker.c_str(), mCfg_mqtt->port);
             mClient->setBufferSize(MQTT_MAX_PACKET_SIZE);
 
             setCallback(std::bind(&PubMqtt<HMSYSTEM>::cbMqtt, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
@@ -107,7 +107,7 @@ class PubMqtt {
             return mTxCnt;
         }
 
-        void sendMqttDiscoveryConfig(const char *topic) {
+        void sendMqttDiscoveryConfig(String topic) {
             DPRINTLN(DBG_VERBOSE, F("sendMqttDiscoveryConfig"));
 
             char stateTopic[64], discoveryTopic[64], buffer[512], name[32], uniq_id[32];
@@ -173,23 +173,21 @@ class PubMqtt {
                 if(strlen(mDevName) > 0) {
                     // der Server und der Port müssen neu gesetzt werden,
                     // da ein MQTT_CONNECTION_LOST -3 die Werte zerstört hat.
-                    mClient->setServer(mCfg_mqtt->broker, mCfg_mqtt->port);
+                    mClient->setServer(mCfg_mqtt->broker.c_str(), mCfg_mqtt->port);
                     mClient->setBufferSize(MQTT_MAX_PACKET_SIZE);
 
-                    char lwt[MQTT_TOPIC_LEN + 7 ]; // "/uptime" --> + 7 byte
-                    snprintf(lwt, MQTT_TOPIC_LEN + 7, "%s/uptime", mCfg_mqtt->topic);
+                    String lwt = mCfg_mqtt->topic + "/uptime";
 
-                    if((strlen(mCfg_mqtt->user) > 0) && (strlen(mCfg_mqtt->pwd) > 0))
-                        resub = mClient->connect(mDevName, mCfg_mqtt->user, mCfg_mqtt->pwd, lwt, 0, false, "offline");
+                    if((mCfg_mqtt->user.length() > 0) && (strlen(mCfg_mqtt->pwd) > 0))
+                        resub = mClient->connect(mDevName, mCfg_mqtt->user.c_str(), mCfg_mqtt->pwd, lwt.c_str(), 0, false, "offline");
                     else
-                        resub = mClient->connect(mDevName, lwt, 0, false, "offline");
+                        resub = mClient->connect(mDevName, lwt.c_str(), 0, false, "offline");
                         // ein Subscribe ist nur nach einem connect notwendig
                     if(resub) {
-                        char topic[MQTT_TOPIC_LEN + 13 ]; // "/devcontrol/#" --> + 6 byte
                         // ToDo: "/devcontrol/#" is hardcoded
-                        snprintf(topic, MQTT_TOPIC_LEN + 13, "%s/devcontrol/#", mCfg_mqtt->topic);
-                        DPRINTLN(DBG_INFO, F("subscribe to ") + String(topic));
-                        mClient->subscribe(topic); // subscribe to mTopic + "/devcontrol/#"
+                        String topic = mCfg_mqtt->topic + "/devcontrol/#"; // "/devcontrol/#"
+                        DPRINTLN(DBG_INFO, F("subscribe to ") + topic);
+                        mClient->subscribe(&topic); // subscribe to mTopic + "/devcontrol/#"
                     }
                 }
             }
diff --git a/src/web/web.cpp b/src/web/web.cpp
index 45be992e..ce7e7bf8 100644
--- a/src/web/web.cpp
+++ b/src/web/web.cpp
@@ -434,11 +434,12 @@ void web::showSave(AsyncWebServerRequest *request) {
         if(request->arg("mqttAddr") != "") {
             String addr = request->arg("mqttAddr");
             addr.trim();
-            addr.toCharArray(mConfig->mqtt.broker, MQTT_ADDR_LEN);
-            request->arg("mqttUser").toCharArray(mConfig->mqtt.user, MQTT_USER_LEN);
+            mConfig->mqtt.broker = addr;
+
+            mConfig->mqtt.user = request->arg("mqttUser");
             if(request->arg("mqttPwd") != "{PWD}")
                 request->arg("mqttPwd").toCharArray(mConfig->mqtt.pwd, MQTT_PWD_LEN);
-            request->arg("mqttTopic").toCharArray(mConfig->mqtt.topic, MQTT_TOPIC_LEN);
+            mConfig->mqtt.topic = request->arg("mqttTopic");
             mConfig->mqtt.port = request->arg("mqttPort").toInt();
         }