diff --git a/Firmware/Marlin_main.cpp b/Firmware/Marlin_main.cpp
index a0ef55910..651aeb812 100755
--- a/Firmware/Marlin_main.cpp
+++ b/Firmware/Marlin_main.cpp
@@ -1014,11 +1014,19 @@ void setup()
 	lcd_splash();
     Sound_Init();                                // also guarantee "SET_OUTPUT(BEEPER)"
 
+	selectedSerialPort = eeprom_read_byte((uint8_t *)EEPROM_SECOND_SERIAL_ACTIVE);
+	if (selectedSerialPort == 0xFF) selectedSerialPort = 0;
+	eeprom_update_byte((uint8_t *)EEPROM_SECOND_SERIAL_ACTIVE, selectedSerialPort);
+	MYSERIAL.begin(BAUDRATE);
+	fdev_setup_stream(uartout, uart_putchar, NULL, _FDEV_SETUP_WRITE); //setup uart out stream
+	stdout = uartout;
+
 #ifdef W25X20CL
     bool w25x20cl_success = w25x20cl_init();
+	uint8_t optiboot_status = 1;
 	if (w25x20cl_success)
 	{
-	    optiboot_w25x20cl_enter();
+		optiboot_status = optiboot_w25x20cl_enter();
 #if (LANG_MODE != 0) //secondary language support
         update_sec_lang_from_external_flash();
 #endif //(LANG_MODE != 0)
@@ -1040,15 +1048,13 @@ void setup()
 	if ((farm_mode == 0xFF && farm_no == 0) || ((uint16_t)farm_no == 0xFFFF)) 
 		farm_mode = false; //if farm_mode has not been stored to eeprom yet and farm number is set to zero or EEPROM is fresh, deactivate farm mode
 	if ((uint16_t)farm_no == 0xFFFF) farm_no = 0;
-	
-	selectedSerialPort = eeprom_read_byte((uint8_t*)EEPROM_SECOND_SERIAL_ACTIVE);
-	if (selectedSerialPort == 0xFF) selectedSerialPort = 0;
 	if (farm_mode)
 	{
 		no_response = true; //we need confirmation by recieving PRUSA thx
 		important_status = 8;
 		prusa_statistics(8);
 		selectedSerialPort = 1;
+		MYSERIAL.begin(BAUDRATE);
 #ifdef TMC2130
 		//increased extruder current (PFW363)
 		tmc2130_current_h[E_AXIS] = 36;
@@ -1062,12 +1068,12 @@ void setup()
           if(!(eeprom_read_byte((uint8_t*)EEPROM_FAN_CHECK_ENABLED)))
                eeprom_update_byte((unsigned char *)EEPROM_FAN_CHECK_ENABLED,true);
 	}
-	MYSERIAL.begin(BAUDRATE);
-	fdev_setup_stream(uartout, uart_putchar, NULL, _FDEV_SETUP_WRITE); //setup uart out stream
 #ifndef W25X20CL
 	SERIAL_PROTOCOLLNPGM("start");
-#endif //W25X20CL
-	stdout = uartout;
+#else
+	if ((optiboot_status != 0) || (selectedSerialPort != 0))
+		SERIAL_PROTOCOLLNPGM("start");
+#endif
 	SERIAL_ECHO_START;
 	printf_P(PSTR(" " FW_VERSION_FULL "\n"));
 
diff --git a/Firmware/optiboot_w25x20cl.cpp b/Firmware/optiboot_w25x20cl.cpp
index 584c32fed..dce4074e1 100644
--- a/Firmware/optiboot_w25x20cl.cpp
+++ b/Firmware/optiboot_w25x20cl.cpp
@@ -99,9 +99,11 @@ struct block_t;
 extern struct block_t *block_buffer;
 
 //! @brief Enter an STK500 compatible Optiboot boot loader waiting for flashing the languages to an external flash memory.
-void optiboot_w25x20cl_enter()
+//! @return 1 if "start\n" was not sent. Optiboot was skipped
+//! @return 0 if "start\n" was sent. Optiboot ran normally. No need to send "start\n" in setup()
+uint8_t optiboot_w25x20cl_enter()
 {
-  if (boot_app_flags & BOOT_APP_FLG_USER0) return;
+  if (boot_app_flags & BOOT_APP_FLG_USER0) return 1;
   uint8_t ch;
   uint8_t rampz = 0;
   register uint16_t address = 0;
@@ -120,38 +122,46 @@ void optiboot_w25x20cl_enter()
     unsigned long  boot_timer = 0;
     const char    *ptr = entry_magic_send;
     const char    *end = strlen_P(entry_magic_send) + ptr;
-    // Initialize the serial line.
-    UCSR0A |= (1 << U2X0);
-    UBRR0L = (((float)(F_CPU))/(((float)(115200))*8.0)-1.0+0.5);
-    UCSR0B = (1 << RXEN0) | (1 << TXEN0);
+    const uint8_t selectedSerialPort_bak = selectedSerialPort;
     // Flush the serial line.
     while (RECV_READY) {
       watchdogReset();
       // Dummy register read (discard)
       (void)(*(char *)UDR0);
     }
+    selectedSerialPort = 0; //switch to Serial0
+    MYSERIAL.flush(); //clear RX buffer
+    int SerialHead = rx_buffer.head;
     // Send the initial magic string.
     while (ptr != end)
       putch(pgm_read_byte(ptr ++));
     watchdogReset();
-    // Wait for one second until a magic string (constant entry_magic) is received
+    // Wait for two seconds until a magic string (constant entry_magic) is received
     // from the serial line.
     ptr = entry_magic_receive;
     end = strlen_P(entry_magic_receive) + ptr;
     while (ptr != end) {
-      while (! RECV_READY) {
+      while (rx_buffer.head == SerialHead) {
         watchdogReset();
         delayMicroseconds(1);
         if (++ boot_timer > boot_timeout)
+        {
           // Timeout expired, continue with the application.
-          return;
+          selectedSerialPort = selectedSerialPort_bak; //revert Serial setting
+          return 0;
+        }
       }
-      ch = UDR0;
+      ch = rx_buffer.buffer[SerialHead];
+      SerialHead = (unsigned int)(SerialHead + 1) % RX_BUFFER_SIZE;
       if (pgm_read_byte(ptr ++) != ch)
+      {
           // Magic was not received correctly, continue with the application
-          return;
+          selectedSerialPort = selectedSerialPort_bak; //revert Serial setting
+          return 0;
+      }
       watchdogReset();
     }
+    cbi(UCSR0B, RXCIE0); //disable the MarlinSerial0 interrupt
     // Send the cfm magic string.
     ptr = entry_magic_cfm;
     while (ptr != end)
diff --git a/Firmware/optiboot_w25x20cl.h b/Firmware/optiboot_w25x20cl.h
index dc7d4395c..95c6465f3 100644
--- a/Firmware/optiboot_w25x20cl.h
+++ b/Firmware/optiboot_w25x20cl.h
@@ -1,6 +1,6 @@
 #ifndef OPTIBOOT_W25X20CL_H
 #define OPTIBOOT_W25X20CL_H
 
-extern void optiboot_w25x20cl_enter();
+extern uint8_t optiboot_w25x20cl_enter();
 
 #endif /* OPTIBOOT_W25X20CL_H */