Our team is currently trying to troubleshoot why a few of our Muon/M404 devices (dual radio (Wi-Fi/cellular)) keep going offline and getting stuck in what seems to be "listening mode” for Wi-Fi. Every 15 minutes or so, a royal blue color flashes for a minute or so and goes away. There are currently no credentials for Wi-Fi written into our firmware, which makes me assume that’s why our device is looping and stuck in an “offline” status despite being powered on. I’m curious to know if anyone has ran into similar issues, and if so discovered what the root cause was? We have some theories about a possible power spike causing a brownout reset, but are still testing this. Also, would adjusting the firmware prevent this loop from happening again if the device resets?
The best way to troubleshoot this is to get a USB serial debugging log using
SerialLogHandler logHandler(LOG_LEVEL_TRACE);
My guess is that the device is unable to connect to cellular and it is attempting to connect to Wi-Fi, but can't because there are no credentials set. However that doesn't make sense because it shouldn't even be attempting to connect to Wi-Fi with no credentials, so that's why the log would be useful.
I should clarify one thing here: the credentials don’t have to be explicitly written into user firmware. They can be set one time via CLI or web setup and stored in non-volatile memory across reboots and updates. It’s not immediately obvious that a device has WiFi credentials stored.
You can use the particle wifi list CLI command with the device plugged in via USB to view these saved credentials.