Unexpected behaviour during TCP communication

[Roman Veselskyi]

Hey team,

We're having trouble with our device. It's been working fine, sending messages to our backend without a hitch. But after a while, it starts having problems connecting to the socket. We're seeing error 116.

<err> rest_client: Failed to connect socket, error: 116
<err> rest_client: rest_client_do_api_call() failed, err -111

#define ETIMEDOUT 116		/* Connection timed out */
#define ECONNREFUSED 111	/* Connection refused */

In our firmware, we've tried implementing a retry cycle, but it hasn't been effective. The modem keeps encountering this error repeatedly. The only solution seems to be rebooting the device.

We don't think the problem lies with our backend because we've encountered the same error when trying to connect to api.nfrcloud.com.

This issue has occurred on two different networks in two different countries and the main point it always disappear after rebooting. 

Could you please review the trace collected from the modem? Thank you.

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_OFFLOAD=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y
CONFIG_NET_NATIVE=n

#Rest client config
CONFIG_REST_CLIENT=y

CONFIG_HTTP_CLIENT=y

The modem firmware is 1.3.4
SDK 2.0.2

[Naeem Maroof]

Hi Roman,

I have forwarded the query to the modem team.

Meanwhile, can you answer following regarding this:

We're having trouble with our device. It's been working fine,

1) Are these custom boards? Did you get them reviewed?

2) Have they (your devices) been working for long?

3) When the problem started to occur? Did you do some updates (in the firmware, mfw, sdk) and then it occurred, or what?

4) As you said that "only solution is rebooting". After rebooting, do you still see the problem? after how long the problem occurs?

5) Is this problem happening with all devices, or just two devices? How many devices you have by the way. You have also mentioned about two locations and two networks. How many different locations your devices are employed in and are some working fine with other networks?

I will provide more input to the modem team after your response and elaboration.

Regards, 

Naeem