Openthread stop working after "Update OpenThread revision #23632"

[retfie]

Describe the bug
Build lwm2m_client sample with OpenThread support, and manually commission it via shell.
Instead of joining already available network, it creates a new segment with the same network parameters and set his state as Leader instead of Child as with before this change. Besides it gets IP from the same local-mesh segment It's unable to ping border router IP or any node in this network.

To Reproduce
cp samples/net/sockets/echo_client/overlay-ot.conf samples/net/lwm2m_client
west build -b nrf52840_pca10056 samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-ot.conf"
west flash --hex-file build/zephyr/zephyr.hex

ot thread stop
ot channel
ot paind
ot extpanid
ot masterkey
ot networkname
ot thread start

Look for messages like:
net_l2_openthread: State changed! Flags: 0x000012a4 Current role: 2

Expected behavior
Current role, should change from 0 up to 2 or 3 and join existing network (in very close proximity) and not going to 4 (Leader) and form a new one, not reachable from other nodes in this network.

When module openthread is checkout at it's previous hash (3c6191eb4e8ca44b5f4eeaa696837bce14e83c69) everything works fine and node was able to connect and register with LWM2M server.

Impact
Openthread is not functional with this change.

Environment (please complete the following information):

• OS: Linux
• Zephyr version: 2.2.99
• Commit SHA: 0095dae

[rlubos]

Hi, there was a change in the usptream OpenThread in default mbedTLS configuration, this can cause compability issues (in general cryptography does not work as expected). I'll open a PR with a fix soon.

[rlubos]

Please give #23688 a try.

[retfie]

Hi Robert,
this PR #23688 fixes the problem, thanks !

[ghlualven]

@retfie Hi, did you get the on-mesh prefixed address (fd11:22) from BR? I cannot on my side and do not know why. #23703

[retfie]

@lualven-duplicate sorry for late response, but yes, I've got on-mesh prefixed address, and I can ping it from BR.