Two issues

Not for tour board I’m afraid. As I said I’m not familiar with your board. I could explain how to do it for an ESP32 with SIM800 GSM module, but that wouldn’t help you because your board uses a totally different library.

Pete.

Please see Nano 33 iot can't send floats - #5 by vshymanskyy

The good news is that the first of the two issues has been resolved.

But the second problem still remains,
I recently installed an LTE antenna on the board.
Previously, the connection time was around 20-30 minutes, but after installing the antenna, it increased to at least 3 hours and up to 12+ hours.
However, I still can’t get a perfectly continuous connection.

We believe this issue is related to the network connection and will be doing further research.