AT%PERIODICSEARCHCONF=0,0,0,0,"1,20,600" - but with pretty low signals, I don't see more than one search

[Achim Kraus]

nRF9160, mfw 1.3.7, NCS 2.9.2

Case:

The modem first connects to LTE-M (Germany, band 3), pretty well.

Then the modem is moved into a building basement (band 8 or 20), with that the modem get's unregistered with the next sent message and starts one network search. That's not successful, maybe because of very low signals (-125 dBm and less), so also somehow OK. But then I don't detect any network search for 1h (instead of my configuration, which in my interpretation of the documentation should trigger new searchs after 10 minutes sleeps). After that hour, the device gives up and reboots ... and then after a couple of minutes (2-5) finds a network.

So, why does the modem not start the configured follow up network searches? Is there something as an optimization "no networks => no new search"?

(Unfortunately, I'm not able to provide modem-traces, at least that will be very, very complicated.)   

[Achim Kraus]

I changed the test:

The modem is now restarted after 2h instead of 1h. Unfortunately, that doesn't change the experience. No success even in the double time, but success after reboot.