nrf9160 takes tens of minutes to finish searching and connect to LTE after hard fault

RE: nrf9160 takes tens of minutes to finish searching and connect to LTE after hard fault

liteyear — Mon, 09 Aug 2021 10:29:52 GMT

Oh really? Sounds plausible, but isn't it kind of unrealistic to expect a mobile cellular device to close connections cleanly? There are many more scenarios that would result in a connection being abandoned than deliberately closed.

I will try to stop crashing so frequently if the Zephyr and ncs developers could just try to stop introducing so many bugs into their libraries ;-)

Maybe what is more practical is to prevent an immediate reconnect attempt after a hard fault. Surely you don't get banned on your first crash?

RE: nrf9160 takes tens of minutes to finish searching and connect to LTE after hard fault

liteyear — Mon, 09 Aug 2021 10:24:06 GMT

Ah, hadn't heard of that one. Will definitely give it a shot next time. Maybe I'm unlucky, but if this is is, then it seems to be both extremely easy to trigger, and murderously hard to notice! There are various unclear mentions of long protection periods across these forums but this is the first definitive clue. Cross fingers this could be a huge help.

RE: nrf9160 takes tens of minutes to finish searching and connect to LTE after hard fault

Didrik Rokhaug — Mon, 09 Aug 2021 09:16:13 GMT

Hi,

In addition to Markus' suggestion, you might have triggered the modem's reset loop protection.

Could you try to subscribe to %MDMEV notifications?

It will tell you if you have triggered the reset loop restriction.

You can read more about the reset loop restriction here: https://infocenter.nordicsemi.com/topic/nwp_042/WP/nwp_042/intro.html

Best regards,

Didrik

RE: nrf9160 takes tens of minutes to finish searching and connect to LTE after hard fault

Markus Tacker (he/him) — Mon, 09 Aug 2021 07:26:30 GMT

This might be cause by your network operator blocking the device because it might not be behaving correctly. A crash might cause the existing connection to not be cleaned up properly, nor to timeout, and the immediate reconnect (and maybe multiple of those per hour) could make the network mark the device as block for a certain amount of time.

Try to avoid crashing your device frequently.

Firmware updates gracefully shut down the connection, that's why that works without issues.