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).