Hello all,

I am experimenting with the LwM2M client example on a B-L475E-IOT01A board. Based on the lwm2m example that comes with Zephyr I have modified it and added code that initializes the Wi-Fi subsystem prior to the lwm2m setup. The code of the function can be found here:

https://github.com/cvasilak/zephyr-lwm2m-client/blob/master/src/lwm2m-client.c#L94-L140

It is based on some networking example snippet found around the net. I can see from the logs that the connection to the WIFI succeeds and an IP address is assigned to the board (I can ping the board from another machine) . Unfortunately, the LwM2M subsystem complains with the following error when trying to establish a connection:
..
00:00:25.263,000] <err> net_lwm2m_engine: fcntl(F_GETFL) failed (-22)
[00:00:25.296,000] <err> net_lwm2m_rd_client: Cannot init LWM2M engine ()
..

Here are the full logs:

*** Booting Zephyr OS build zephyr-v3.2.0-3154-g3c4783042eed ***
[00:00:00.546,000] <dbg> net_lwm2m_engine: lwm2m_engine_init: LWM2M engine socket receive thread started
[00:00:00.546,000] <dbg> net_lwm2m_obj_security: security_create: Create LWM2M security instance: 0
[00:00:00.546,000] <dbg> net_lwm2m_obj_server: server_create: Create LWM2M server instance: 0
[00:00:00.546,000] <dbg> net_lwm2m_obj_device: device_create: Create LWM2M device instance: 0
[00:00:00.546,000] <dbg> net_lwm2m_obj_firmware: firmware_create: Create LWM2M firmware instance: 0
[00:00:00.546,000] <inf> net_lwm2m_client_app: Initializing network connection...
Connected
[00:00:07.554,000] <inf> net_lwm2m_client_app: Connected to network
[00:00:07.554,000] <inf> net_lwm2m_client_app: Your address: 192.168.1.43
[00:00:07.554,000] <inf> net_lwm2m_client_app: Lease time: 0 seconds
[00:00:07.554,000] <inf> net_lwm2m_client_app: Subnet: 0.0.0.0
[00:00:07.554,000] <inf> net_lwm2m_client_app: Router: 0.0.0.0
[00:00:07.554,000] <inf> net_lwm2m_client_app: Run LWM2M client
[00:00:07.554,000] <dbg> net_lwm2m_registry: lwm2m_engine_set: path:0/0/2, value:0x2000d497, len:1
[00:00:07.554,000] <dbg> net_lwm2m_registry: lwm2m_engine_set: path:0/0/10, value:0x2000d496, len:2
[00:00:07.554,000] <dbg> net_lwm2m_registry: lwm2m_engine_set: path:1/0/0, value:0x2000d496, len:2
[00:00:07.557,000] <dbg> net_lwm2m_registry: lwm2m_engine_create_obj_inst: path:3303/0
[00:00:07.557,000] <dbg> net_ipso_temp_sensor: temp_sensor_create: Create IPSO Temperature Sensor instance: 0
[00:00:07.557,000] <dbg> net_lwm2m_registry: lwm2m_engine_create_obj_inst: path:3311/0
[00:00:07.557,000] <dbg> net_ipso_light_control: light_control_create: Create IPSO Light Control instance: 0
[00:00:07.557,000] <dbg> net_lwm2m_registry: lwm2m_engine_create_obj_inst: path:3340/0
[00:00:07.557,000] <dbg> net_ipso_timer: timer_inst_create: Create IPSO Timer instance: 0
[00:00:07.557,000] <inf> net_lwm2m_rd_client: Start LWM2M Client: disco_l475_iot1
[00:00:07.557,000] <dbg> net_lwm2m_registry: lwm2m_engine_set: path:3303/0/5700, value:0x2000d8f0, len:8
[00:00:08.547,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:0/0/1, buf:0x2000bfa7, buflen:1
[00:00:08.547,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:0/0/10, buf:0x2000bfde, buflen:2
[00:00:08.547,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:1/0/1, buf:0x2000bfb0, buflen:4
[00:00:08.548,000] <inf> net_lwm2m_rd_client: RD Client started with endpoint 'disco_l475_iot1' with client lifetime 30
[00:00:08.548,000] <dbg> net_lwm2m_message_handling: lwm2m_parse_peerinfo: Parse url: coap://192.168.1.28
[00:00:08.649,000] <err> net_lwm2m_engine: fcntl(F_GETFL) failed (-22)
[00:00:08.679,000] <err> net_lwm2m_rd_client: Cannot init LWM2M engine (-22)
[00:00:09.679,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:0/0/1, buf:0x2000bfa7, buflen:1
[00:00:09.679,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:0/0/10, buf:0x2000bfde, buflen:2
[00:00:09.679,000] <dbg> net_lwm2m_registry: lwm2m_engine_get: path:1/0/1, buf:0x2000bfb0, buflen:4
[00:00:09.679,000] <inf> net_lwm2m_rd_client: RD Client started with endpoint 'disco_l475_iot1' with client lifetime 30
[00:00:09.679,000] <dbg> net_lwm2m_message_handling: lwm2m_parse_peerinfo: Parse url: coap://192.168.1.28
[00:00:09.772,000] <err> net_lwm2m_engine: fcntl(F_GETFL) failed (-22)
[00:00:09.803,000] <err> net_lwm2m_rd_client: Cannot init LWM2M engine (-22)
...

As I mentioned earlier, pinging the board from my development machine works.

...
$ ping 192.168.1.43
PING 192.168.1.43 (192.168.1.43) 56(84) bytes of data.
64 bytes from 192.168.1.43: icmp_seq=1 ttl=255 time=8.96 ms
64 bytes from 192.168.1.43: icmp_seq=2 ttl=255 time=4.30 ms
...

In contrast,  trying to ping from the board (using the network shell) I get this:

...
uart:~$ net ping 192.168.1.1
PING 192.168.1.1
Failed to send ping, err: -134
...

I am newbie to Zephyr and possibly miss something obvious, will appreciate any help

Kind regards,
-Christos