Matter devices typically communicate within the local network, but sometimes you need to reach the internet, whether for telemetry, cloud services, or custom functionality. This post explains how to send UDP traffic from a Matter-over-Thread device through a Thread Border Router using NAT64, with working code on the nRF54LM20 DK.

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Matter-over-Thread devices are designed to operate locally, with hubs handling internet communication. But when direct internet access is needed for telemetry or custom cloud services, Thread Border Routers can bridge the gap via NAT64. The post explains the networking stack (Thread, IPv6, NAT64, UDP), walks through a working UDP echo example on the nRF54LM20 DK using OpenThread's DNS client and UDP APIs, and covers practical constraints like payload size limits and the absence of TCP/TLS. For production use, CoAP over DTLS is recommended as a lightweight, encrypted protocol layer that runs over UDP.

Connecting Matter-over-Thread Devices to the Internet