Help with CoAP Client Sample on nRF9160 DK Using Jio NB-IoT SIM

[Arun_538]

Hi Nordic team,

I'm using the nRF9160 DK with nRF Connect SDK v2.9.1, and trying to run the coap_client sample to send a GET request to the public CoAP test server at coap.me (IP: 134.102.218.18), targeting the resource path /hello.

I'm using a Jio NB-IoT SIM for LTE connectivity.

I’ve configured the sample as follows:

Enabled CONFIG_COAP_CLIENT=y

Set CONFIG_COAP_SERVER_HOSTNAME="coap.me"

Set CONFIG_COAP_SERVER_PORT=5683

Enabled CONFIG_LTE_LINK_CONTROL=y and CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

Using conn_mgr to establish the LTE connection before sending the CoAP request

I would like to ask:

Is there anything specific I need to change to get communication working with a CoAP server like coap.me?

Has anyone successfully used NB-IoT (especially with Jio SIM) to send CoAP requests over UDP?

Are there any known limitations or additional requirements for using NB-IoT for CoAP communication?

Thanks and regards,
Arun

[Achim Kraus]

Let me recommend:

First check, if the modem registers successful to a network, e.g. enable the modem trace and use the cellular monitor.

Does it register? If not, it's related to you SIM card and the available networks.

> Has anyone successfully used NB-IoT (especially with Jio SIM) to send CoAP requests over UDP?

Not with that SIM. With a couple of other SIMs, if there is a subscribed NB-IoT network reachable, it works. UDP is nothing special on that level. I use CoAP via cellular (nRF9160) for a couple of years. It's superior in terms of data-volume and energy, especially, if encryption is required, DTLS 1.2 CID does a good job (RFC9146, I'm one of the co-autors, so I'm biased).

[Arun_538]

Hi,

My setup:

• LTE network registration is successful

• DNS resolution of coap.me works

• IPv4 address is found

• But the CoAP request fails with error: -114 (ENETUNREACH)

  Has anyone successfully sent UDP CoAP packets using any Indian NB-IoT SIM (Vodafone, BSNL, etc.)?

[Arun_538]

Yes, I’m using NCS 2.9.1 with the sample located at:
nrf/samples/net/coap_client

I only modified these two Kconfig values: 

CONFIG_COAP_SAMPLE_SERVER_HOSTNAME="coap.me"
CONFIG_COAP_SAMPLE_RESOURCE="hello"

[Achim Kraus]

west build -d build_nrf9160dk_nrf9160_ns -b nrf9160dk/nrf9160/ns --pristine -- -DCONFIG_COAP_SAMPLE_SERVER_HOSTNAME='"coap.me"' -DCONFIG_COAP_SAMPLE_RESOURCE='"hello"' -DSNIPPET="nrf91-modem-trace-uart"

will enable the modem trace.

coap.pcapng.gz

(My modem uses currently LTE-M, in my experience in Europe, there is no difference according UDP, except that LTE-M has a lower latency.)

[Arun_538]

still facing 

*** Booting nRF Connect SDK v2.9.1-60d0d6c8d42d ***
*** Using Zephyr OS v3.7.99-ca954a6216c9 ***
[00:00:00.389,739] <inf> coap_client_sample: The CoAP client sample started
[00:00:00.389,770] <inf> coap_client_sample: Bringing network interface up and connecting to the network
[00:00:00.723,083] <inf> coap_client_sample: Waiting for network connectivity
[00:01:16.345,245] <wrn> nrf_modem_lib_netif: No IPv4 address given by the network
[00:01:16.411,895] <inf> coap_client_sample: Network connectivity established
[00:01:16.616,424] <inf> coap_client_sample: IPv4 Address found 134.102.218.18
[00:01:16.616,729] <inf> coap_client_sample: Initializing CoAP client
[00:01:16.618,347] <err> coap_client_sample: Failed to send request: -114
[00:01:16.618,347] <err> coap_client_sample: periodic_coap_request_loop, error: -114
[00:01:16.618,347] <err> coap_client_sample: Fatal error! Rebooting the device*** Booting nRF Connect SDK v2.9.1-60d0d6c8d42d ***
*** Using Zephyr OS v3.7.99-ca954a6216c9 ***
[00:00:00.253,295] <inf> coap_client_sample: The CoAP client sample started
[00:00:00.253,326] <inf> coap_client_sample: Bringing network interface up and connecting to the network
[00:00:00.584,411] <inf> coap_client_sample: Waiting for network connectivity
[00:01:21.317,138] <wrn> nrf_modem_lib_netif: No IPv4 address given by the network
[00:01:21.388,763] <inf> coap_client_sample: Network connectivity established
[00:01:21.738,281] <inf> coap_client_sample: IPv4 Address found 134.102.218.18
[00:01:21.738,555] <inf> coap_client_sample: Initializing CoAP client
[00:01:21.740,173] <err> coap_client_sample: Failed to send request: -114
[00:01:21.740,203] <err> coap_client_sample: periodic_coap_request_loop, error: -114
[00:01:21.740,203] <err> coap_client_sample: Fatal error! Rebooting the device

[Arun_538]

I forgot to mention — I'm actually using the nRF9151 DK, not the nRF9160.

From what I understand, the nRF9151 is fully compatible with the nrf9160dk_nrf9160_ns build target, and no changes to the configuration are required for this sample. Please correct me if I'm wrong.

[Achim Kraus]

west build -b nrf9151dk/nrf9151/ns --pristine -- -DCONFIG_COAP_SAMPLE_SERVER_HOSTNAME='"coap.me"' -DCONFIG_COAP_SAMPLE_RESOURCE='"hello"' -DSNIPPET="nrf91-modem-trace-uart" -DCONFIG_LTE_NETWORK_MODE_NBIOT=y

(you may skip the -DCONFIG_LTE_NETWORK_MODE_NBIOT=y, I just add this to force my modem in NB-IoT mode.)

coap-nbiot.pcapng.gz

Edited: just in the case you're not common with using the modem trace and export capture in wireshark.

Modem Trace, see DevAcademy - Modem Trace

Export Captures, see Logs and IP Capturing ‐ How To Provide The Right Information - Wireshark.