MKR NB 1500 Freeze if I insert a different sim card.

I have an Arduino MKR1500 NB board. Firstly I used with a Vodafone NB-IOT sim card, with this working well without issues.
But If I insert a different NB-IOT sim cards, it freeze after 5-10 sec and doesn't response answer to at commands. I have a telekom and hologram sim card.
I have a SIMCOM 7020 modem and in this working perfectly all sim so the cards are ok!

Does anyone have any idea what could be wrong?

I am using this very simple code and I using the serial monitor for the at commands.

// baud rate used for both Serial ports
unsigned long baud = 115200;

void setup() {
  digitalWrite(SARA_RESETN, LOW);

  // Send Poweron pulse
  digitalWrite(SARA_PWR_ON, HIGH);


void loop() {
  if (Serial.available()) {

  if (SerialSARA.available()) {

Thanks for posting that comments bakonyip95. Sorry, I don't have any solution for you. I've had to include a watchdog in my setup to re-try if I don't get a connection (and it locks up). Not a great solution.

I've had all sorts of problems with NB 1500 boards. So was thinking about converting to use something with a SIM 7020E. Which Arduino are you using with your 7020 and which library?

BTW I use Vodafone and I'm connecting through to Azure IOT hub. Moderately successful with the NB 1500 but often has trouble re-connecting.

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