Cannot connect to LTE after trying to disconnect/reconnect 30 times

[jgv_sl_bolt]

Hello,

I came across a very consistent bug that occurs on the nRF9160DK and a custom board with an nRF9160.

Basically, if you try to send the AT commands "AT+CFUN=1" and "AT+CFUN=4" 30 times, it cannot establish a registered LTE connection and searches perpetually. Before the 30th time, it is able to register a connection properly:

But after the 30th time:

You have to reset the board for it to work again.

Does anyone have an idea to why this happens? And why 30 times?

[Sigurd]

Hi,

This is the GSMA specified Radio Policy Manager (RPM) feature which is blocking the ATTACH command. RPM is used for protecting the network from excessive signalling loads in various scenarios. In this case default value 30 is used for PDP Context Activation Requests (TS.34_8.2.4_REQ_010, See page 43 in this pdf)

Edit: There is a bug in modem fw v1.0.x were the PDP Context Activation Requests counter is not reset after 1 hours. This is fixed in modem fw v1.1.0

[jgv_sl_bolt]

Hmm, but it says 30 per hour? I'm able to bypass it by simply resetting the board and thus going over the limit. Or is this all regulated within the nRF9160 itself?

[Sigurd]

jgv_sl_bolt said:

Or is this all regulated within the nRF9160 itself?

Correct, it's implemented in the modem firmware. If you power-cycle your board, this counter will also be reset.

[arthurkoroghlian]

Is the fix for this truly to reset the board after the 30th request ?  We are running into the identical issue at the moment.  

[jlangballeswift]

I'm getting the same issue but I'm disconnecting and reconnecting every 30 minutes, so it takes 15 hours to reach the 30 ATTACH limit. The pdf there says 30 per hour, but I'm doing just 2 per hour, so I thought I wouldn't hit the limit. Is this a bug in the modem firmware? Is there a way to work around? My use-case is basically getting GPS and pushing to the cloud periodically with a sleep state in-between.