nRF9160 NB IoT failure to connect China Mobile

RE: nRF9160 NB IoT failure to connect China Mobile

Didrik Rokhaug — Mon, 22 Jan 2024 13:38:20 GMT

Can you take a modem trace, so we can look closer at the communication with the cellular network?

RE: nRF9160 NB IoT failure to connect China Mobile

Lebedek — Thu, 18 Jan 2024 17:33:46 GMT

implemented PDN but still DNS error. see the log. We use Soracom SIM with NB IOT in China devzone.nordicsemi.com/.../20240118_2800_1_29002800_1_2900_.log

RE: nRF9160 NB IoT failure to connect China Mobile

Lebedek — Tue, 16 Jan 2024 17:20:21 GMT

Implemented China Telecom ZZHC, still fails to connect but I see now the "Err -2"; what doe sit mean? will try next with PDN enabled.

I:DtLTE: Active LTE mode changed: NB-IoT
I:DtLTE: RSRP = -90
D:DtLTE: Network registration status: Connected - roaming
D:DtLTE: PSM parameter update: TAU: 1800, Active time: -1

D:DtLTE: CEREG: Registration status: 5
D:DtLTE: CEREG: Device is registered on the network
E:DtLTE: getaddrinfo for www.gov.cn failed, err = -2
E:DtLTE: getaddrinfo for www.china.org.cn failed, err = -2

RE: nRF9160 NB IoT failure to connect China Mobile

Didrik Rokhaug — Mon, 15 Jan 2024 09:48:43 GMT

Hi,

[quote user=""]D:DtLTE: CEREG: Device is registered on the network
E:DtLTE: getaddrinfo() for www.gov.cn failed, err 0[/quote]

The log shows that you are connected to the cellular network, but that your DNS lookups fails.

One common cause for this in NB-IoT networks is that the network might not support ePCO.

Could you try to enable the modem to use "legacy" PCO instead?

You can either use the %XPCO AT command directly, or use the PDN library.

CONFIG_PDN=y

CONFIG_PDN_LEGACY_PCO=y

Best regards,

Didrik

RE: nRF9160 NB IoT failure to connect China Mobile

sly — Sun, 14 Jan 2024 22:24:35 GMT

Additionally, i want to make sure that you are enabling the China Telecom ZZHC Library (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.4.0-rc2/nrf/libraries/modem/zzhc.html) since this is not configured by default for any of our samples or applications out of the box in our SDK.

Cheers

Mike

RE: nRF9160 NB IoT failure to connect China Mobile

sly — Sun, 14 Jan 2024 20:36:22 GMT

Hi Alex,

Can you confirm that your carrier or MVNO has support for NB-IoT in the region of China that you are testing in?

Thank you for the log file.

Can you use our Cellular Monitor tool inside of nRF Connect for Desktop suite of tools to capture a modem trace? At first glance, it looks like you have some cloud certificate issues. I recommend working with your carrier partner in China to drill down further. Please attach a mode trace but we have also made it easier for your team to analyze the modem trace.

Regards,

Mike