MKR1400 We couldn't connect to the GSM network.

Same issue here, anyone had a reply from support yet?

Can establish connection with my own sketch, sending TCP data to server. Can't connect to IoT though.

Tried two different SIMs (that work sending data via TCP) with both the IoT configuration wizzard and uploading an example IoT sketch.

/* 
  Sketch generated by the Arduino IoT Cloud Thing "LED"
  https://create.arduino.cc/cloud/things/1e8c45b0-af74-4a62-8a0d-82492683e169 

  Arduino IoT Cloud Properties description

  The following variables are automatically generated and updated when changes are made to the Thing properties

  bool ledSwitch;

  Properties which are marked as READ/WRITE in the Cloud Thing will also have functions
  which are called when their values are changed from the Dashboard.
  These functions are generated with the Thing and added at the end of this sketch.
*/

#include "thingProperties.h"

void setup() {
  // Initialize serial and wait for port to open:
  Serial.begin(9600);
  // This delay gives the chance to wait for a Serial Monitor without blocking if none is found
  delay(1500); 

  // Defined in thingProperties.h
  initProperties();

  // Connect to Arduino IoT Cloud
  ArduinoCloud.begin(ArduinoIoTPreferredConnection);
  ledSwitch = false;
  
  /*
     The following function allows you to obtain more information
     related to the state of network and IoT Cloud connection and errors
     the higher number the more granular information you’ll get.
     The default is 0 (only errors).
     Maximum is 4
 */
  setDebugMessageLevel(2);
  ArduinoCloud.printDebugInfo();
}

void loop() {
  ArduinoCloud.update();
 
}


void onLedSwitchChange() {
  digitalWrite(LED_BUILTIN,ledSwitch);
}

The former just returns a failed connection attempt, the latter returns this in the serial monitor with nothing else happening:

[ 13051 ] SIM card ok
[ 13051 ] Connecting to Cellular Network
[ 17179 ] GPRS.attachGPRS(): 4
[ 17179 ] Sending PING to outer space...
[ 17886 ] GSM.ping(): 81
[ 17886 ] Connected to GPRS Network
[ 17889 ] Connecting to Arduino IoT Cloud...