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On this page we answer the Frequently Asked Questions.

For each question we list a few options which should solve your issue.
If you still have a problem after trying out all options, post a message on our forum.

Can't upload a new sketch

  • Update to the latest version of the Arduino IDE.
  • For Windows use the installer, not the Windows Store App.
  • Follow the getting started guide to verify you use the correct URL and update your boardfiles to the latest version.
  • Double press the reset button to manually put it into bootloader mode.

My Board isn't replying on AT commands

  • Remove your SIM card.
  • Upload the passthrough sketch.
  • Send the command AT+CFUN=15.
  • Update the u-blox firmware.


Check if the zero-ohm resistor is placed.

If it isn't placed and you don't have a zero-ohm resistor, you can connect the two pins by making a solder bridge.



The MQTT example in the R4X library is using the URCs.
If the example hangs on connecting to the MQTT broker, then it's mostliky the "URC" issue.

DEBUG output:

Network connected
>> AT+UMQTT=2,"",1883
<< +UMQTT: 2,1
<< OK
<< +UMQTTC: 1,1
<< OK
MQTT failed
Setup done