Intermittent CoAP ACK Reception Issues with Multiple nRF52840 Nodes in Thread Network

[cedriczou13]

Hello,

I am experiencing an issue with my OpenThread network that consists of a Raspberry Pi acting as a border router and multiple nRF52840 nodes. The setup works perfectly with a single child node sending CoAP messages to a cloud server every 30 seconds, with acknowledgments (ACKs) being consistently received. However, when I expand the network by adding four more nRF52840 nodes, I start facing intermittent problems. Specifically, after some time, one or more nodes stop receiving ACKs for their CoAP messages, leading to unreliable data transmission.

Network Setup:

• Border Router: Raspberry Pi (serving as the OpenThread Border Router)
• Child Nodes: 5 x nRF52840 boards, configured to send CoAP messages to a cloud server every 30 seconds.

Observed Behavior:

• With a single child node, there are no issues.
• Adding four more nodes initially works fine, but eventually, one or more nodes intermittently fail to receive ACKs for their CoAP messages.
• Temporarily resolving the issue by resetting the affected device(s), after which they begin to receive ACKs again, but the problem eventually recurs.

I appreciate any guidance or insights you can provide to help resolve this intermittent ACK reception problem. Thank you for your support.

[jwhui]

What git commit are you using?

Can you provide logs and packet captures to provide more visibility?