When executing a UDP to the mle-eid IP, a "No Route" error occurred.

[jiemincao]

When using the UDP, the leader discovered that certain routes were unreachable. After checking the logs, a "No Route" error was found. Upon further investigation, it was determined that when a child switches to a new parent, its router information is not updated in the leader's EID Cache Table, causing this issue.

The currently known solution is to have the child send a UDP to the leader, which triggers the leader to update its EID Cache Table. However, if no IP message is received from the child, the leader will continue to drop packets. It is unclear whether there are other possible solutions.

We are currently using the Thread Reference version 2023-07-06. Has this issue been resolved in a newer version?

The log is as follows:
[N] MeshForwarder-: Dropping IPv6 UDP msg, len:57, chksum:7258, ecn:no, sec:yes, error:NoRoute, prio:normal
[N] MeshForwarder-: src:[fd00:db8:0:0:0:ff:fe00:fc00]:5683
[N] MeshForwarder-: dst:[fd00:db8:0:0:0:0:0:104]:5683

[aaa147147]

I have encountered this problem before, and updating to the latest version looks much more stable. I suggest you update to the latest version.
And it is also best to update the Openthread version of Thread devices to the latest version

[jiemincao]

Thank you for the response. I will proceed with the update and testing.