diff --git a/.github/workflows/cpplint.yml b/.github/workflows/cpplint.yml
index 0514bb81..af5e8b79 100644
--- a/.github/workflows/cpplint.yml
+++ b/.github/workflows/cpplint.yml
@@ -18,4 +18,4 @@ jobs:
           pip install cpplint
       - name: Linting
         run: |
-          cpplint --repository=. --recursive --filter=-runtime/references,-readability/braces,-whitespace,-legal,-build/include ./src ./include ./lib/Hoymiles ./lib/MqttSubscribeParser ./lib/TimeoutHelper ./lib/ResetReason
+          cpplint --repository=. --recursive --filter=-build/c++11,-runtime/references,-readability/braces,-whitespace,-legal,-build/include ./src ./include ./lib/Hoymiles ./lib/MqttSubscribeParser ./lib/TimeoutHelper ./lib/ResetReason
diff --git a/include/MessageOutput.h b/include/MessageOutput.h
index a47b0278..7c56a6f4 100644
--- a/include/MessageOutput.h
+++ b/include/MessageOutput.h
@@ -4,14 +4,15 @@
 #include <AsyncWebSocket.h>
 #include <HardwareSerial.h>
 #include <Stream.h>
+#include <mutex>
 
 #define BUFFER_SIZE 500
 
 class MessageOutputClass : public Print {
 public:
-    MessageOutputClass();
     void loop();
-    size_t write(uint8_t c);
+    size_t write(uint8_t c) override;
+    size_t write(const uint8_t *buffer, size_t size) override;
     void register_ws_output(AsyncWebSocket* output);
 
 private:
@@ -21,7 +22,7 @@ private:
     uint32_t _lastSend = 0;
     bool _forceSend = false;
 
-    SemaphoreHandle_t _lock;
+    std::mutex _msgLock;
 };
 
 extern MessageOutputClass MessageOutput;
\ No newline at end of file
diff --git a/include/MqttSettings.h b/include/MqttSettings.h
index 6653d75a..af48ea5e 100644
--- a/include/MqttSettings.h
+++ b/include/MqttSettings.h
@@ -5,6 +5,7 @@
 #include <MqttSubscribeParser.h>
 #include <Ticker.h>
 #include <espMqttClient.h>
+#include <mutex>
 
 class MqttSettingsClass {
 public:
@@ -38,6 +39,7 @@ private:
     String willTopic;
     Ticker mqttReconnectTimer;
     MqttSubscribeParser _mqttSubscribeParser;
+    std::mutex _clientLock;
     bool _verboseLogging = true;
 };
 
diff --git a/lib/Hoymiles/src/HoymilesRadio.cpp b/lib/Hoymiles/src/HoymilesRadio.cpp
index a8cc0f51..77fa609b 100644
--- a/lib/Hoymiles/src/HoymilesRadio.cpp
+++ b/lib/Hoymiles/src/HoymilesRadio.cpp
@@ -99,7 +99,7 @@ void HoymilesRadio::handleReceivedPackage()
         }
     } else if (!_busyFlag) {
         // Currently in idle mode --> send packet if one is in the queue
-        if (!_commandQueue.empty()) {
+        if (!isQueueEmpty()) {
             CommandAbstract* cmd = _commandQueue.front().get();
 
             auto inv = Hoymiles.getInverterBySerial(cmd->getTargetAddress());
diff --git a/lib/Hoymiles/src/HoymilesRadio.h b/lib/Hoymiles/src/HoymilesRadio.h
index 21477293..2322ab95 100644
--- a/lib/Hoymiles/src/HoymilesRadio.h
+++ b/lib/Hoymiles/src/HoymilesRadio.h
@@ -5,7 +5,7 @@
 #include "commands/CommandAbstract.h"
 #include "types.h"
 #include <memory>
-#include <queue>
+#include <ThreadSafeQueue.h>
 
 class HoymilesRadio {
 public:
@@ -17,10 +17,15 @@ public:
     bool isInitialized();
 
     template <typename T>
-    T* enqueCommand()
+    void enqueCommand(std::shared_ptr<T> cmd)
     {
-        _commandQueue.push(std::make_shared<T>());
-        return static_cast<T*>(_commandQueue.back().get());
+        _commandQueue.push(cmd);
+    }
+
+    template <typename T>
+    std::shared_ptr<T> prepareCommand()
+    {
+        return std::make_shared<T>();
     }
 
 protected:
@@ -34,7 +39,7 @@ protected:
     void handleReceivedPackage();
 
     serial_u _dtuSerial;
-    std::queue<std::shared_ptr<CommandAbstract>> _commandQueue;
+    ThreadSafeQueue<std::shared_ptr<CommandAbstract>> _commandQueue;
     bool _isInitialized = false;
     bool _busyFlag = false;
 
diff --git a/lib/Hoymiles/src/inverters/HMS_Abstract.cpp b/lib/Hoymiles/src/inverters/HMS_Abstract.cpp
index 326ac839..f67ff11b 100644
--- a/lib/Hoymiles/src/inverters/HMS_Abstract.cpp
+++ b/lib/Hoymiles/src/inverters/HMS_Abstract.cpp
@@ -18,9 +18,10 @@ bool HMS_Abstract::sendChangeChannelRequest()
         return false;
     }
 
-    ChannelChangeCommand* cmdChannel = _radio->enqueCommand<ChannelChangeCommand>();
+    auto cmdChannel = _radio->prepareCommand<ChannelChangeCommand>();
     cmdChannel->setChannel(HoymilesRadio_CMT::getChannelFromFrequency(Hoymiles.getRadioCmt()->getInverterTargetFrequency()));
     cmdChannel->setTargetAddress(serial());
+    _radio->enqueCommand(cmdChannel);
 
     return true;
 };
diff --git a/lib/Hoymiles/src/inverters/HMT_Abstract.cpp b/lib/Hoymiles/src/inverters/HMT_Abstract.cpp
index b561ee7f..c345be97 100644
--- a/lib/Hoymiles/src/inverters/HMT_Abstract.cpp
+++ b/lib/Hoymiles/src/inverters/HMT_Abstract.cpp
@@ -20,9 +20,10 @@ bool HMT_Abstract::sendChangeChannelRequest()
         return false;
     }
 
-    ChannelChangeCommand* cmdChannel = _radio->enqueCommand<ChannelChangeCommand>();
+    auto cmdChannel = _radio->prepareCommand<ChannelChangeCommand>();
     cmdChannel->setChannel(HoymilesRadio_CMT::getChannelFromFrequency(Hoymiles.getRadioCmt()->getInverterTargetFrequency()));
     cmdChannel->setTargetAddress(serial());
+    _radio->enqueCommand(cmdChannel);
 
     return true;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_Abstract.cpp b/lib/Hoymiles/src/inverters/HM_Abstract.cpp
index 47acfbba..dd3af728 100644
--- a/lib/Hoymiles/src/inverters/HM_Abstract.cpp
+++ b/lib/Hoymiles/src/inverters/HM_Abstract.cpp
@@ -29,9 +29,10 @@ bool HM_Abstract::sendStatsRequest()
     time_t now;
     time(&now);
 
-    RealTimeRunDataCommand* cmd = _radio->enqueCommand<RealTimeRunDataCommand>();
+    auto cmd = _radio->prepareCommand<RealTimeRunDataCommand>();
     cmd->setTime(now);
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
 
     return true;
 }
@@ -60,9 +61,10 @@ bool HM_Abstract::sendAlarmLogRequest(bool force)
     time_t now;
     time(&now);
 
-    AlarmDataCommand* cmd = _radio->enqueCommand<AlarmDataCommand>();
+    auto cmd = _radio->prepareCommand<AlarmDataCommand>();
     cmd->setTime(now);
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
     EventLog()->setLastAlarmRequestSuccess(CMD_PENDING);
 
     return true;
@@ -82,13 +84,15 @@ bool HM_Abstract::sendDevInfoRequest()
     time_t now;
     time(&now);
 
-    DevInfoAllCommand* cmdAll = _radio->enqueCommand<DevInfoAllCommand>();
+    auto cmdAll = _radio->prepareCommand<DevInfoAllCommand>();
     cmdAll->setTime(now);
     cmdAll->setTargetAddress(serial());
+    _radio->enqueCommand(cmdAll);
 
-    DevInfoSimpleCommand* cmdSimple = _radio->enqueCommand<DevInfoSimpleCommand>();
+    auto cmdSimple = _radio->prepareCommand<DevInfoSimpleCommand>();
     cmdSimple->setTime(now);
     cmdSimple->setTargetAddress(serial());
+    _radio->enqueCommand(cmdSimple);
 
     return true;
 }
@@ -107,9 +111,10 @@ bool HM_Abstract::sendSystemConfigParaRequest()
     time_t now;
     time(&now);
 
-    SystemConfigParaCommand* cmd = _radio->enqueCommand<SystemConfigParaCommand>();
+    auto cmd = _radio->prepareCommand<SystemConfigParaCommand>();
     cmd->setTime(now);
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
     SystemConfigPara()->setLastLimitRequestSuccess(CMD_PENDING);
 
     return true;
@@ -132,9 +137,10 @@ bool HM_Abstract::sendActivePowerControlRequest(float limit, PowerLimitControlTy
     _activePowerControlLimit = limit;
     _activePowerControlType = type;
 
-    ActivePowerControlCommand* cmd = _radio->enqueCommand<ActivePowerControlCommand>();
+    auto cmd = _radio->prepareCommand<ActivePowerControlCommand>();
     cmd->setActivePowerLimit(limit, type);
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
     SystemConfigPara()->setLastLimitCommandSuccess(CMD_PENDING);
 
     return true;
@@ -161,9 +167,10 @@ bool HM_Abstract::sendPowerControlRequest(bool turnOn)
         _powerState = 0;
     }
 
-    PowerControlCommand* cmd = _radio->enqueCommand<PowerControlCommand>();
+    auto cmd = _radio->prepareCommand<PowerControlCommand>();
     cmd->setPowerOn(turnOn);
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
     PowerCommand()->setLastPowerCommandSuccess(CMD_PENDING);
 
     return true;
@@ -177,9 +184,10 @@ bool HM_Abstract::sendRestartControlRequest()
 
     _powerState = 2;
 
-    PowerControlCommand* cmd = _radio->enqueCommand<PowerControlCommand>();
+    auto cmd = _radio->prepareCommand<PowerControlCommand>();
     cmd->setRestart();
     cmd->setTargetAddress(serial());
+    _radio->enqueCommand(cmd);
     PowerCommand()->setLastPowerCommandSuccess(CMD_PENDING);
 
     return true;
diff --git a/lib/ThreadSafeQueue/ThreadSafeQueue.h b/lib/ThreadSafeQueue/ThreadSafeQueue.h
new file mode 100644
index 00000000..9a195c60
--- /dev/null
+++ b/lib/ThreadSafeQueue/ThreadSafeQueue.h
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include <mutex>
+#include <optional>
+#include <queue>
+
+template <typename T>
+class ThreadSafeQueue {
+public:
+    ThreadSafeQueue() = default;
+    ThreadSafeQueue(const ThreadSafeQueue<T>&) = delete;
+    ThreadSafeQueue& operator=(const ThreadSafeQueue<T>&) = delete;
+
+    ThreadSafeQueue(ThreadSafeQueue<T>&& other)
+    {
+        std::lock_guard<std::mutex> lock(_mutex);
+        _queue = std::move(other._queue);
+    }
+
+    virtual ~ThreadSafeQueue() { }
+
+    unsigned long size() const
+    {
+        std::lock_guard<std::mutex> lock(_mutex);
+        return _queue.size();
+    }
+
+    std::optional<T> pop()
+    {
+        std::lock_guard<std::mutex> lock(_mutex);
+        if (_queue.empty()) {
+            return {};
+        }
+        T tmp = _queue.front();
+        _queue.pop();
+        return tmp;
+    }
+
+    void push(const T& item)
+    {
+        std::lock_guard<std::mutex> lock(_mutex);
+        _queue.push(item);
+    }
+
+    T front()
+    {
+        std::lock_guard<std::mutex> lock(_mutex);
+        return _queue.front();
+    }
+
+private:
+    // Moved out of public interface to prevent races between this
+    // and pop().
+    bool empty() const
+    {
+        return _queue.empty();
+    }
+
+    std::queue<T> _queue;
+    mutable std::mutex _mutex;
+};
diff --git a/src/MessageOutput.cpp b/src/MessageOutput.cpp
index dc9c6715..23c644bc 100644
--- a/src/MessageOutput.cpp
+++ b/src/MessageOutput.cpp
@@ -8,17 +8,6 @@
 
 MessageOutputClass MessageOutput;
 
-#define MSG_LOCK() \
-    do {           \
-    } while (xSemaphoreTake(_lock, portMAX_DELAY) != pdPASS)
-#define MSG_UNLOCK() xSemaphoreGive(_lock)
-
-MessageOutputClass::MessageOutputClass()
-{
-    _lock = xSemaphoreCreateMutex();
-    MSG_UNLOCK();
-}
-
 void MessageOutputClass::register_ws_output(AsyncWebSocket* output)
 {
     _ws = output;
@@ -27,10 +16,9 @@ void MessageOutputClass::register_ws_output(AsyncWebSocket* output)
 size_t MessageOutputClass::write(uint8_t c)
 {
     if (_buff_pos < BUFFER_SIZE) {
-        MSG_LOCK();
+        std::lock_guard<std::mutex> lock(_msgLock);
         _buffer[_buff_pos] = c;
         _buff_pos++;
-        MSG_UNLOCK();
     } else {
         _forceSend = true;
     }
@@ -38,11 +26,23 @@ size_t MessageOutputClass::write(uint8_t c)
     return Serial.write(c);
 }
 
+size_t MessageOutputClass::write(const uint8_t* buffer, size_t size)
+{
+    std::lock_guard<std::mutex> lock(_msgLock);
+    if (_buff_pos + size < BUFFER_SIZE) {
+        memcpy(&_buffer[_buff_pos], buffer, size);
+        _buff_pos += size;
+    }
+    _forceSend = true;
+
+    return Serial.write(buffer, size);
+}
+
 void MessageOutputClass::loop()
 {
     // Send data via websocket if either time is over or buffer is full
     if (_forceSend || (millis() - _lastSend > 1000)) {
-        MSG_LOCK();
+        std::lock_guard<std::mutex> lock(_msgLock);
         if (_ws && _buff_pos > 0) {
             _ws->textAll(_buffer, _buff_pos);
             _buff_pos = 0;
@@ -50,7 +50,6 @@ void MessageOutputClass::loop()
         if (_forceSend) {
             _buff_pos = 0;
         }
-        MSG_UNLOCK();
         _forceSend = false;
     }
 }
\ No newline at end of file
diff --git a/src/MqttSettings.cpp b/src/MqttSettings.cpp
index e432e061..befa930f 100644
--- a/src/MqttSettings.cpp
+++ b/src/MqttSettings.cpp
@@ -32,21 +32,30 @@ void MqttSettingsClass::onMqttConnect(bool sessionPresent)
     const CONFIG_T& config = Configuration.get();
     publish(config.Mqtt_LwtTopic, config.Mqtt_LwtValue_Online);
 
-    for (const auto& cb : _mqttSubscribeParser.get_callbacks()) {
-        mqttClient->subscribe(cb.topic.c_str(), cb.qos);
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient != nullptr) {
+        for (const auto& cb : _mqttSubscribeParser.get_callbacks()) {
+            mqttClient->subscribe(cb.topic.c_str(), cb.qos);
+        }
     }
 }
 
 void MqttSettingsClass::subscribe(const String& topic, uint8_t qos, const espMqttClientTypes::OnMessageCallback& cb)
 {
     _mqttSubscribeParser.register_callback(topic.c_str(), qos, cb);
-    mqttClient->subscribe(topic.c_str(), qos);
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient != nullptr) {
+        mqttClient->subscribe(topic.c_str(), qos);
+    }
 }
 
 void MqttSettingsClass::unsubscribe(const String& topic)
 {
     _mqttSubscribeParser.unregister_callback(topic.c_str());
-    mqttClient->unsubscribe(topic.c_str());
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient != nullptr) {
+        mqttClient->unsubscribe(topic.c_str());
+    }
 }
 
 void MqttSettingsClass::onMqttDisconnect(espMqttClientTypes::DisconnectReason reason)
@@ -99,6 +108,12 @@ void MqttSettingsClass::performConnect()
         using std::placeholders::_4;
         using std::placeholders::_5;
         using std::placeholders::_6;
+
+        std::lock_guard<std::mutex> lock(_clientLock);
+        if (mqttClient == nullptr) {
+            return;
+        }
+
         MessageOutput.println("Connecting to MQTT...");
         const CONFIG_T& config = Configuration.get();
         _verboseLogging = config.Mqtt_VerboseLogging;
@@ -135,6 +150,10 @@ void MqttSettingsClass::performDisconnect()
 {
     const CONFIG_T& config = Configuration.get();
     publish(config.Mqtt_LwtTopic, config.Mqtt_LwtValue_Offline);
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient == nullptr) {
+        return;
+    }
     mqttClient->disconnect();
 }
 
@@ -150,6 +169,10 @@ void MqttSettingsClass::performReconnect()
 
 bool MqttSettingsClass::getConnected()
 {
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient == nullptr) {
+        return false;
+    }
     return mqttClient->connected();
 }
 
@@ -160,6 +183,11 @@ String MqttSettingsClass::getPrefix()
 
 void MqttSettingsClass::publish(const String& subtopic, const String& payload)
 {
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient == nullptr) {
+        return;
+    }
+
     String topic = getPrefix();
     topic += subtopic;
 
@@ -171,6 +199,10 @@ void MqttSettingsClass::publish(const String& subtopic, const String& payload)
 
 void MqttSettingsClass::publishGeneric(const String& topic, const String& payload, bool retain, uint8_t qos)
 {
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient == nullptr) {
+        return;
+    }
     mqttClient->publish(topic.c_str(), qos, retain, payload.c_str());
 }
 
@@ -190,8 +222,11 @@ void MqttSettingsClass::loop()
 
 void MqttSettingsClass::createMqttClientObject()
 {
-    if (mqttClient != nullptr)
+    std::lock_guard<std::mutex> lock(_clientLock);
+    if (mqttClient != nullptr) {
         delete mqttClient;
+        mqttClient = nullptr;
+    }
     const CONFIG_T& config = Configuration.get();
     if (config.Mqtt_Tls) {
         mqttClient = new espMqttClientSecure(espMqttClientTypes::UseInternalTask::NO);
diff --git a/webapp/package.json b/webapp/package.json
index de16badd..e5c687b1 100644
--- a/webapp/package.json
+++ b/webapp/package.json
@@ -26,7 +26,7 @@
     "@rushstack/eslint-patch": "^1.3.2",
     "@tsconfig/node18": "^18.2.0",
     "@types/bootstrap": "^5.2.6",
-    "@types/node": "^20.4.5",
+    "@types/node": "^20.4.6",
     "@types/sortablejs": "^1.15.1",
     "@types/spark-md5": "^3.0.2",
     "@vitejs/plugin-vue": "^4.2.3",
diff --git a/webapp/yarn.lock b/webapp/yarn.lock
index 97a9f0ff..c7562bc8 100644
--- a/webapp/yarn.lock
+++ b/webapp/yarn.lock
@@ -382,10 +382,10 @@
   resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.11.tgz#d421b6c527a3037f7c84433fd2c4229e016863d3"
   integrity sha512-wOuvG1SN4Us4rez+tylwwwCV1psiNVOkJeM3AUWUNWg/jDQY2+HE/444y5gc+jBmRqASOm2Oeh5c1axHobwRKQ==
 
-"@types/node@^20.4.5":
-  version "20.4.5"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-20.4.5.tgz#9dc0a5cb1ccce4f7a731660935ab70b9c00a5d69"
-  integrity sha512-rt40Nk13II9JwQBdeYqmbn2Q6IVTA5uPhvSO+JVqdXw/6/4glI6oR9ezty/A9Hg5u7JH4OmYmuQ+XvjKm0Datg==
+"@types/node@^20.4.6":
+  version "20.4.6"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-20.4.6.tgz#b66b66c9bb5d49b199f03399e341c9d6036e9e88"
+  integrity sha512-q0RkvNgMweWWIvSMDiXhflGUKMdIxBo2M2tYM/0kEGDueQByFzK4KZAgu5YHGFNxziTlppNpTIBcqHQAxlfHdA==
 
 "@types/semver@^7.3.12":
   version "7.3.13"