diff --git a/platformio.ini b/platformio.ini
index 936d5fa7..5fd9ef9e 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -26,7 +26,7 @@ description = Paxcounter is a proof-of-concept ESP32 device for metering passeng
 
 [common]
 ; for release_version use max. 10 chars total, use any decimal format like "a.b.c"
-release_version = 1.5.9
+release_version = 1.5.13
 ; DEBUG LEVEL: For production run set to 0, otherwise device will leak RAM while running!
 ; 0=None, 1=Error, 2=Warn, 3=Info, 4=Debug, 5=Verbose
 debug_level = 0
diff --git a/src/button.cpp b/src/button.cpp
index 42f4180f..37ae91fe 100644
--- a/src/button.cpp
+++ b/src/button.cpp
@@ -6,6 +6,8 @@
 // Local logging tag
 static const char TAG[] = "main";
 
+portMUX_TYPE mutexButton = portMUX_INITIALIZER_UNLOCKED;
+
 void IRAM_ATTR ButtonIRQ() {
   portENTER_CRITICAL(&mutexButton);
   ButtonPressedIRQ++;
diff --git a/src/cyclic.cpp b/src/cyclic.cpp
index 0e49726a..1e864ba5 100644
--- a/src/cyclic.cpp
+++ b/src/cyclic.cpp
@@ -9,6 +9,8 @@
 // Local logging tag
 static const char TAG[] = "main";
 
+portMUX_TYPE mutexHomeCycle = portMUX_INITIALIZER_UNLOCKED;
+
 // do all housekeeping
 void doHousekeeping() {
 
diff --git a/src/display.cpp b/src/display.cpp
index 9e2ffcb2..773dbf94 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -15,6 +15,8 @@ const char lora_datarate[] = {"100908078CNA121110090807"};
 
 uint8_t volatile DisplayState = 0;
 
+portMUX_TYPE mutexDisplay = portMUX_INITIALIZER_UNLOCKED;
+
 // helper function, prints a hex key on display
 void DisplayKey(const uint8_t *key, uint8_t len, bool lsb) {
   const uint8_t *p;
diff --git a/src/globals.h b/src/globals.h
index a4fffd4d..739512f1 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -46,7 +46,6 @@ extern uint16_t volatile macs_total, macs_wifi, macs_ble,
     batt_voltage;               // display values
 extern std::set<uint16_t> macs; // temp storage for MACs
 extern hw_timer_t *channelSwitch, *sendCycle;
-extern portMUX_TYPE mutexButton, mutexDisplay, mutexHomeCycle, mutexSendCycle;
 extern volatile uint8_t SendCycleTimerIRQ, HomeCycleIRQ, DisplayTimerIRQ,
     ChannelTimerIRQ, ButtonPressedIRQ;
 
diff --git a/src/hal/lopy4.h b/src/hal/lopy4.h
index 5a4fffa0..fc0be422 100644
--- a/src/hal/lopy4.h
+++ b/src/hal/lopy4.h
@@ -3,7 +3,7 @@
 #define HAS_LORA 1       // comment out if device shall not send data via LoRa
 #define HAS_SPI 1        // comment out if device shall not send data via SPI
 #define CFG_sx1276_radio 1
-#define HAS_LED NOT_A_PIN // LoPy4 has no on board mono LED, we use on board RGB LED
+//#define HAS_LED NOT_A_PIN // LoPy4 has no on board mono LED, we use on board RGB LED
 #define HAS_RGB_LED   GPIO_NUM_0  // WS2812B RGB LED on GPIO0
 #define BOARD_HAS_PSRAM // use extra 4MB extern RAM
 
diff --git a/src/hal/ttgov21old.h b/src/hal/ttgov21old.h
index ce92a8a4..25271b80 100644
--- a/src/hal/ttgov21old.h
+++ b/src/hal/ttgov21old.h
@@ -7,6 +7,7 @@
 #define HAS_SPI 1        // comment out if device shall not send data via SPI
 #define CFG_sx1276_radio 1 // HPD13A LoRa SoC
 #define HAS_LED NOT_A_PIN // no usable LED on board
+#define DISABLE_BROWNOUT 1 // comment out if you want to keep brownout feature
 
 #define HAS_DISPLAY U8X8_SSD1306_128X64_NONAME_HW_I2C
 //#define DISPLAY_FLIP  1 // rotated display
diff --git a/src/main.cpp b/src/main.cpp
index d150928a..f758a795 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -30,7 +30,7 @@ Task          Core  Prio  Purpose
 IDLE          0     0     ESP32 arduino scheduler -> runs wifi sniffer task
 gpsloop       0     2     read data from GPS over serial or i2c
 IDLE          1     0     Arduino loop() -> used for LED switching
-loraloop      1     3     runs the LMIC stack
+loraloop      1     2     runs the LMIC stack
 statemachine  1     1     switches application process logic
 wifiloop      0     4     rotates wifi channels
 
@@ -77,12 +77,6 @@ QueueHandle_t SPISendQueue;
 TaskHandle_t GpsTask = NULL;
 #endif
 
-// sync main loop and ISR when modifying IRQ handler shared variables
-portMUX_TYPE mutexButton = portMUX_INITIALIZER_UNLOCKED;
-portMUX_TYPE mutexDisplay = portMUX_INITIALIZER_UNLOCKED;
-portMUX_TYPE mutexHomeCycle = portMUX_INITIALIZER_UNLOCKED;
-portMUX_TYPE mutexSendCycle = portMUX_INITIALIZER_UNLOCKED;
-
 std::set<uint16_t> macs; // container holding unique MAC adress hashes
 
 // initialize payload encoder
@@ -312,9 +306,9 @@ void setup() {
   ESP_LOGI(TAG, "Starting Lora...");
   xTaskCreatePinnedToCore(lorawan_loop, /* task function */
                           "loraloop",   /* name of task */
-                          2560,         /* stack size of task */
+                          3048,         /* stack size of task */
                           (void *)1,    /* parameter of the task */
-                          3,            /* priority of the task */
+                          2,            /* priority of the task */
                           &LoraTask,    /* task handle*/
                           1);           /* CPU core */
 #endif
@@ -352,7 +346,7 @@ void setup() {
   // start wifi channel rotation task
   xTaskCreatePinnedToCore(switchWifiChannel, /* task function */
                           "wifiloop",        /* name of task */
-                          1536,              /* stack size of task */
+                          2048,              /* stack size of task */
                           NULL,              /* parameter of the task */
                           4,                 /* priority of the task */
                           &wifiSwitchTask,   /* task handle*/
diff --git a/src/senddata.cpp b/src/senddata.cpp
index 616df8fb..d4f89d62 100644
--- a/src/senddata.cpp
+++ b/src/senddata.cpp
@@ -1,6 +1,8 @@
 // Basic Config
 #include "globals.h"
 
+portMUX_TYPE mutexSendCycle = portMUX_INITIALIZER_UNLOCKED;
+
 // put data to send in RTos Queues used for transmit over channels Lora and SPI
 void SendData(uint8_t port) {
 
diff --git a/src/wifiscan.cpp b/src/wifiscan.cpp
index 621c8494..4e2500b6 100644
--- a/src/wifiscan.cpp
+++ b/src/wifiscan.cpp
@@ -33,9 +33,6 @@ void wifi_sniffer_init(void) {
       // .filter_mask = WIFI_PROMIS_FILTER_MASK_MGMT}; // only MGMT frames
       .filter_mask = WIFI_PROMIS_FILTER_MASK_ALL}; // we use all frames
 
-  // esp_event_loop_init(NULL, NULL);
-  // ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL));
-
   ESP_ERROR_CHECK(esp_wifi_init(&cfg)); // configure Wifi with cfg
   ESP_ERROR_CHECK(
       esp_wifi_set_country(&wifi_country)); // set locales for RF and channels
@@ -50,7 +47,7 @@ void wifi_sniffer_init(void) {
 }
 
 // IRQ Handler
-void ChannelSwitchIRQ() {
+void IRAM_ATTR ChannelSwitchIRQ() {
   BaseType_t xHigherPriorityTaskWoken = pdFALSE;
   // unblock wifi channel rotation task
   xSemaphoreGiveFromISR(xWifiChannelSwitchSemaphore, &xHigherPriorityTaskWoken);
diff --git a/src/wifiscan.h b/src/wifiscan.h
index ea507cd7..48c218a1 100644
--- a/src/wifiscan.h
+++ b/src/wifiscan.h
@@ -27,7 +27,7 @@ typedef struct {
 
 void wifi_sniffer_init(void);
 void IRAM_ATTR wifi_sniffer_packet_handler(void *buff, wifi_promiscuous_pkt_type_t type);
-void ChannelSwitchIRQ(void);
+void IRAM_ATTR ChannelSwitchIRQ(void);
 void switchWifiChannel(void * parameter);
 
 #endif
\ No newline at end of file