Hardware
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Module: Fanstel WT02P40P (dual-band 2.4 GHz / 5 GHz)
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SoC: nRF52 + Wi-Fi coprocessor (WT02 series)
Software
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nRF Connect SDK version: v2.6.2
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OS: Zephyr (default networking stack)
Problem Description
We are facing intermittent issues while establishing a TLS connection to a remote server when the device is connected via a Wi-Fi router network.
The firmware gets stuck at the following API call:
connect(sock, (struct sockaddr *)&server, sizeof(struct sockaddr_in));
In many failure cases, the device reboots unexpectedly while blocked in this call.
Occasionally the connection succeeds, but application-level communication does not occur even after a successful TLS connection.
When using a mobile hotspot, the same firmware works reliably:
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TLS connection succeeds
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Data exchange works as expected
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No unexpected reboots observed
Observed Behavior
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connect()sometimes blocks indefinitely when using a Wi-Fi router -
Device reboots during or after the
connect()call -
In some cases, TLS connection is established, but no data is exchanged
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Behavior is intermittent (sometimes works, often fails)
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Mobile hotspot works consistently with the same firmware and server
Additional BLE Issue
We are also observing a BLE advertising issue:
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After long-term operation (approximately 1–2 days powered ON)
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BLE advertising stops unexpectedly
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Device remains powered but does not advertise anymore
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This happens intermittently
Questions / Assistance Needed
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Are there any known issues with TLS socket connections over certain Wi-Fi routers in nRF Connect SDK v2.6.2?
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Could this be related to Wi-Fi stack timing, memory usage, or TLS configuration?
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Are there recommended configurations or patches for improving TLS stability over router networks?
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Could the BLE advertising stop be related to power management, Wi-Fi coexistence, or resource exhaustion?
Any guidance, debugging suggestions, or known limitations would be greatly appreciated.
