Large Thread Networks

[ahavstad79]

We have been using 70+ nordic nrf52840, to test how capabilities and known constraints when deployed at larger scale network. I find large set of best practices, configuration and setups descriptions for smaller thread networks, but not for larger networks:

Our Testing Context:
We've tested startup patterns, router promotion timing, and child attachment scaling
We're designing for 200-400 devices across segmented Thread networks
We're seeing both successes and specific failure modes that we'd like to address

Questions:

Router Child Capacity & CPU Pressure:
We observe CPU and buffer pressure when a single router handles burst attach storms. Are there published specifications or recommended limits for:
Maximum concurrent child attachment rate per router?
Recommended child count per router for sustained stability (vs. theoretical 512)?
Buffer/queue sizing recommendations during bulk device joins?

Gateway/Coordinator Performance at Scale:
What are the known limitations of ot-br-posix (or nrf gateway solutions) when managing multiple datasets/segments with 100+ devices per segment?
Any known issues with downstream address resolution or device discovery after parent changes?

Configuration Tuning for Large Networks:
Are there undocumented or application-note-only parameters we should be tuning for larger deployments? (e.g., CHILD_TIMEOUT, ROUTER_UPGRADE_THRESHOLD, route refresh intervals)
What jitter and startup delay values does Nordic recommend in practice?

Known Limitations & Roadmap:
Are there known issues with sleepy end-device (SED) downstream behavior, address stability, or topology flapping that we should architect around?
Can Nordic share any internal scaling test data or reference architectures?

What would help most:
Configuration examples or application notes for deployments >100 devices
Honest acknowledgment of known limitations so we can design appropriately
Recommendations on segmentation thresholds or failover strategies