@Stefan-de-Lange Thank you so much, it works now! My message appears at the IoT dashboard or T-Mobile.
The joke is that I bought these modules last Friday, and updating the modem seems very difficult. I would need to do that using a pass through AT+ command method. I will contact Arduino for that. Thanks a lot again! Bert

@Martijn-Kooijman Thanks for the advice! Good to know that current can be lower. I will check mine again. Other issues I had was missing messages, up to 20%! I seem to have solved it by adding a 4 s delay after opening a port (between opening port and sending message). I did that about 12 h ago and still not a single message lost!

@Crowdsourcer said in Arduino MKR NB1500: lukt niet om te verbinden.:

@Martijn-Kooijman @Stefan-de-Lange
Some news after the update (to 2.04): Lowpower.sleep (or deepSleep) has improved by a factor 2! The current reduced to 0.48 mA, still not very low power but at least an improvement.
The command AT+URAT=8 is not recognized anymore (comunication selection for NB only). It also seems that it sometimes needs a lot of time to open a channel after a deep_sleep (varies between 10 s and >30s which wastes energy).

I can confirm now that AT+URAT=8 works with the new firmware! Probably because I changed: AT+UMNOPROF=100 (European profile).