Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

teba99 — Fri, 27 Mar 2026 12:52:04 GMT

Hi Pascal,

Let's close it for now. Thanks

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

Pascal Hdz — Fri, 27 Mar 2026 09:22:17 GMT

Hello Terrence,

Do you need further assistance with this ticket or could we close it?

Regards,

Pascal.

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

Pascal Hdz — Wed, 18 Feb 2026 12:26:00 GMT

Hello Terrence,

The use of the conn_mgr feature is asynchronous, so it depends on the events. The following example demonstrates its use:

https://docs.zephyrproject.org/latest/connectivity/networking/conn_mgr/main.html#usage

Your connection handler should be able to catch the disconnection event (NET_EVENT_L4_DISCONNECTED), and your application/business logic should be able to execute conn_mgr_all_if_connect(true) when it's time to re-establish the connection. Using conn_mgr_all_if_disconnect(true) achieves the same result as using the lte_lc_power_off() wrapper, so for the sake of clarity, you should not combining them neither call them sequentially.

Regards,
Pascal.

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

teba99 — Wed, 18 Feb 2026 09:01:11 GMT

Hi,

Thanks, Pascal. To close the loop on this:

We still see the err: -111 occasionally (with and without SWD) and have not yet been able to reproduce it reliably or find the root cause. Sometimes it recovers by itself, but not always. We have found that the sequence of

conn_mgr_all_if_disconnect(true)

lte_lc_offline()

lte_lc_normal()

conn_mgr_all_if_connect(true)

usually restores the cloud connection in these circumstances (without a reboot).

We will also try MFW 2.0.4.

Best,

Terrence

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

Pascal Hdz — Mon, 16 Feb 2026 18:49:30 GMT

Communication has continued through email.

Summary:

They are using NCS v2.9.0-7787b2649840 which had a bug on how the port value was presented in the serial log, 45858 (0xB322) is 8883 (0x22B3) with bytes swapped due the use of hton. This was fixed in this PR in v3.3.0-preview1:

https://github.com/nrfconnect/sdk-nrf/commit/129b757e1f479e09928f1647f056fcb5a04948ec
I have requested to share a serial log with CONFIG_NRF_CLOUD_LOG_LEVEL_DBG enabled when the error happens.
In a separate board, upgrade MFW to 2.0.4 and try to reproduce the error, share also the log with CONFIG_NRF_CLOUD_LOG_LEVEL_DBG enabled.
The error happens after executing a firmware upgrade of the application through SWD, I recommended to disable both the transmit and receive RF circuits and deactivate LTE and GNSS before executing the reset. This can be achieved by executing lte_lc_power_off() and wait 10 seconds before the reset.

Regards,

Pascal.

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

teba99 — Fri, 06 Feb 2026 15:42:52 GMT

Hi Pascal,

I checked, we don't change the port anywhere. But I think the message about port 45858 may be misleading ... maybe it is an ephemeral local port on the device side?

In any case, I realized the problem is similar to one I reported a couple of months ago. I thought this was a different error, but it seems to be the same: nRF9151 stuck in disconnected, unable to reconnect to LTE-M

We'll investigate this as a combination of SIM/network behavior and trying to reset the TCP connection/modem stack.

Apologies. I think this post can be closed as a duplicate.

Update:

After some more debugging, I believe the issue here is different. The one I reported a few months ago is triggered specifically by SIM issues (e.g. deactivation), and as a follow-on effect may result in err: -111.

In contrast, what I am reporting here is not triggered by SIM issues, but unprompted and seemingly random. "Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111" seems to happen at any time, on any device we are using, independent of the SIM or cellular network. In our device population it is currently happening multiple times a day across devices.

Any advice or insight you have is appreciated.

Thanks

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

Pascal Hdz — Fri, 06 Feb 2026 14:42:56 GMT

There might be something else in your application or configuration that might be changing this value.

Regards,

Pascal.

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

teba99 — Fri, 06 Feb 2026 09:24:40 GMT

Hi Pascal,

We were wondering the same, we are not making any changes to the port or CONFIG_NRF_CLOUD_PORT. In zephyr/autoconf.h I see

#define CONFIG_NRF_CLOUD_PORT 8883

Thanks

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

Pascal Hdz — Fri, 06 Feb 2026 09:09:13 GMT

Hello Terrence,

Why is the port pointing to 45858? It should be 8883. Please verify if the configuration variable

CONFIG_NRF_CLOUD_PORT

has been changed in your project.

Pascal.

RE: Device intermittent failures to connect to nRF Cloud MQTT broker (err: -111)

teba99 — Tue, 03 Feb 2026 15:47:00 GMT

Following up on this: I now have a log that shows the device tries to connect for 10+ minutes and keeps getting err: -111. But suddenly -- without any changes on our side -- the error is gone and the device is able to connect:

[00:01:10.335,998] <inf> poc_app: Connecting over LTE..
[00:01:17.039,184] <inf> poc_app: LTE connection established. Connecting to nRF Cloud..
[00:02:11.483,795] <err> nrf_cloud_transport: Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111
[00:03:17.039,306] <wrn> cloud_connection: Could not connect to nRF Cloud, readiness timeout
[00:03:17.039,337] <wrn> poc_app: Failed to establish connection to nRF Cloud
[00:03:22.039,428] <inf> poc_app: Connecting over LTE..
[00:03:22.048,675] <inf> poc_app: LTE connection established. Connecting to nRF Cloud..
[00:04:16.512,054] <err> nrf_cloud_transport: Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111
[00:05:22.048,767] <wrn> cloud_connection: Could not connect to nRF Cloud, readiness timeout
[00:05:22.048,797] <wrn> poc_app: Failed to establish connection to nRF Cloud
[00:05:27.048,858] <inf> poc_app: Connecting over LTE..
[00:05:27.058,135] <inf> poc_app: LTE connection established. Connecting to nRF Cloud..
[00:06:21.523,834] <err> nrf_cloud_transport: Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111
[00:07:27.058,227] <wrn> cloud_connection: Could not connect to nRF Cloud, readiness timeout
[00:07:27.058,258] <wrn> poc_app: Failed to establish connection to nRF Cloud
[00:07:32.058,349] <inf> poc_app: Connecting over LTE..
[00:07:32.067,596] <inf> poc_app: LTE connection established. Connecting to nRF Cloud..
[00:08:26.502,868] <err> nrf_cloud_transport: Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111
[00:09:32.067,687] <wrn> cloud_connection: Could not connect to nRF Cloud, readiness timeout
[00:09:32.067,718] <wrn> poc_app: Failed to establish connection to nRF Cloud
[00:09:37.067,810] <inf> poc_app: Connecting over LTE..
[00:09:37.077,087] <inf> poc_app: LTE connection established. Connecting to nRF Cloud..
[00:10:31.627,929] <err> nrf_cloud_transport: Could not connect to nRF Cloud MQTT Broker mqtt.nrfcloud.com, port: 45858. err: -111
[00:11:37.077,178] <wrn> cloud_connection: Could not connect to nRF Cloud, readiness timeout
[00:11:37.077,209] <wrn> poc_app: Failed to establish connection to nRF Cloud
[00:11:42.077,301] <inf> poc_app: Connecting over LTE..
[00:11:42.086,578] <inf> poc_app: LTE connection established. Connecting to nRF Cloud.
[00:12:16.288,696] <inf> cloud_connection: Connection to nRF Cloud established and ready