Unable to receive UDP messages when thread is active.

Question

Hi,

I built a Thread Network using two nRF52840-DKs with the OpenThread CLI sample written.
After making each thread active, we opened a UDP socket and sent a message to the multicast address (ff02::1).
At this time, no log indicating reception was displayed on the other nRF52840-DK.
I can confirm using Wireshark that the UDP message can be sent reliably.

Also, when sending the same message after inactivating Thread with "ot thread stop", a log showing receipt was displayed.
Is there a way to receive UDP messages with Thread active?

Below are the respective CLI logs.

<< commissioner size log >>

*** Booting Zephyr OS build v3.3.99-ncs1 ***


uart:~$ ot thread stop
Done
uart:~$ ot dataset init new
Done
uart:~$ ot dataset channel 11
Done
uart:~$ ot dataset panid 0x1234
Done
uart:~$ ot dataset commit active
Done
uart:~$ ot ifconfig up
Done
uart:~$ ot thread start
Done
uart:~$ ot dataset
Active Timestamp: 1
Channel: 11
Channel Mask: 0x07fff800
Ext PAN ID: de1372f2690746ac
Mesh Local Prefix: fd87:e652:47f:59ee::/64
Network Key: 8e70238e21f467005ca0f012a2f544f2
Network Name: OpenThread-158d
PAN ID: 0x1234
PSKc: b0164bbfe9e483a4c4a7d2b1b389db3d
Security Policy: 672 onrc
Done
uart:~$ ot commissioner start
Commissioner: petitioning
Done
Commissioner: active
uart:~$ ot commissioner joiner add f4ce364117e9f1a4 N0RD1C
Done
Commissioner: Joiner start 237c8fef269a5885
Commissioner: Joiner connect 237c8fef269a5885
Commissioner: Joiner finalize 237c8fef269a5885
Commissioner: Joiner end 237c8fef269a5885
Commissioner: Joiner remove 237c8fef269a5885
uart:~$ ot udp open
Done
uart:~$ ot udp linksecurity disable
Done
uart:~$ ot udp send ff02::1 test1
Error 7: InvalidArgs
uart:~$ ot udp send ff02::1 2378 test1
Done
uart:~$ ot udp send ff02::1 2378 test2
Done
uart:~$ ot udp send ff02::1 2378 test3
Done
uart:~$ ot udp bind :: 2378
Done
uart:~$ ot thread stop
Done
5 bytes from fe80:0:0:0:e0e0:a6a0:5e93:1294 2378 test3
uart:~$ ot thread start
Done
uart:~$ ot ipaddr
fd87:e652:47f:59ee:0:ff:fe00:7800
fd87:e652:47f:59ee:0:ff:fe00:fc35
fd87:e652:47f:59ee:df22:d48b:3815:3dfd
fe80:0:0:0:4c7c:380a:7beb:2442
Done
Commissioner: disabled
uart:~$
uart:~$ ot thread stop
Done
5 bytes from fe80:0:0:0:e0e0:a6a0:5e93:1294 2378 test4
uart:~$

<< joiner side log >>

*** Booting Zephyr OS build v3.3.99-ncs1 ***


uart:~$ ot thread stop
Done
uart:~$ ot dataset init new
Done
uart:~$ ot dataset channel 11
Done
uart:~$ ot dataset panid 0x1234
Done
uart:~$ ot dataset commit active
Done
uart:~$ ot ifconfig up
Done
uart:~$ ot eui64
f4ce364117e9f1a4
Done
uart:~$ ot joiner start N0RD1C
Done
Join success
uart:~$ ot thread start
Done
uart:~$ ot udp open
Done
uart:~$ ot udp linksecurity disable
Done
uart:~$ ot udp bind :: 2378
Done
uart:~$ ot thread stop
Done
5 bytes from fe80:0:0:0:4c7c:380a:7beb:2442 49156 test2
5 bytes from fe80:0:0:0:4c7c:380a:7beb:2442 49156 test3
uart:~$ ot udp send ff02::1 2378 test1
Done
uart:~$ ot udp send ff02::1 2378 test2
Done
uart:~$ ot udp send ff02::1 2378 test3
Done
uart:~$ ot thread start
Done
uart:~$ ot ipaddr
fd87:e652:47f:59ee:0:ff:fe00:5400
fd87:e652:47f:59ee:ca07:9c8:34c3:dd44
fe80:0:0:0:e0e0:a6a0:5e93:1294
Done
uart:~$ ot udp send ff02::1 2378 test3
Done
uart:~$ ot udp send fe80:0:0:0:4c7c:380a:7beb:2442 2378 test4
Done
uart:~$

Best regards,

Yuma