Bug MKRGSM 1400 Hang after a few PUTs

arduino_secrets.h

#pragma once

#define PIN_CODE "0000"

#define APN_NAME "soracom.io"
#define APN_USERNAME "sora"
#define APN_PASSWORD "sora"

SimplePut.ino

/*
  Simple PUT client for ArduinoHttpClient library
  Connects to server once every five seconds, sends a PUT request
  and a request body

 

  created 14 Feb 2016
  by Tom Igoe
  
  update by M. Sibert May 2018
  
  this example is in the public domain
 */
#include <MKRGSM.h> 
#include <ArduinoHttpClient.h>
#include "arduino_secrets.h"

const String serverName(F("httpbin.org"));
const unsigned serverPort = 80;
const String servicePath(F("/put"));

const String GPRS_APN(F(APN_NAME));
const String GPRS_LOGIN(F(APN_USERNAME));
const String GPRS_PASSWORD(F(APN_PASSWORD));

GSM gsm;
GPRS gprs;
GSMClient gprsClient;

void setup() {
  Serial.begin(9600);
  MODEM.begin();

  if (GSM_READY != gsm.begin(PIN_CODE)) {
    Serial.println("No GSM conection!");
  }

  if (GPRS_READY != gprs.attachGPRS(GPRS_APN.c_str(), GPRS_LOGIN.c_str(), GPRS_PASSWORD.c_str())) {
    Serial.println("No GPRS connection!");
  }

/*
  if (!gprsClient.connect(serverName.c_str(), serverPort)) {
    Serial.println("No TCP connection!");
  }

  Serial.println("No TCP connection!");
 */
}

void loop() {
  HttpClient client = HttpClient(gprsClient, serverName, serverPort);
  Serial.println("Making PUT request");

  const String contentType = "application/json";
  const String putData = "{ \"name\": \"light\", \"age\": 46 }";

  client.put(servicePath.c_str(), contentType, putData);

// read the status code and body of the response
  const int statusCode = client.responseStatusCode();
  const String response = client.responseBody();

  Serial.print("Status code: ");
  Serial.println(statusCode);
  Serial.print("Response: ");
  Serial.println(response);

  Serial.println("Wait five seconds");
  delay(5000);
}