Linux froze and got back working 5 days later, no reboot

Hello my friends,

I’ve come across the weirdest of glitches.

I’m running a simple weather monitor (just temperature) on a Raspbeery Pi 3B (Raspbian Linux 4.14.98-v7+). It has a 3G modem that sends out simple packets to my server at home.

On june 5th I lost remote access to the device. Since it is located somewhere difficult to physically access, I couldn’t manually reboot it.

To my surprise, on June 10th it got back to life. It has not registered a reboot! Here’s the weird excerpt from the log at /var/log/messages:

Jun  5 17:54:28 raspberrypi NetworkManager[345]: <info>  [1559768068.0169] policy: set 'VIVO ZAP' (wwan0) as default for IPv4 routing and DNS
Jun  5 17:54:28 raspberrypi NetworkManager[345]: <info>  [1559768068.0174] dns-mgr: Writing DNS information to /sbin/resolvconf
Jun  5 17:54:28 raspberrypi NetworkManager[345]: <info>  [1559768068.1295] device (ttyUSB2): Activation: successful, device activated.
Jun 10 23:14:33 raspberrypi NetworkManager[345]: <info>  [1560219273.9397] (mon0): using nl80211 for WiFi device control
Jun 10 23:14:33 raspberrypi NetworkManager[345]: <info>  [1560219273.9622] devices added (path: /sys/devices/platform/soc/3f300000.mmc/mmc_host/mmc1/mmc1:0001/mmc1:0001:1/net/mon0, iface: mon0)
Jun 10 23:14:33 raspberrypi NetworkManager[345]: <info>  [1560219273.9623] device added (path: /sys/devices/platform/soc/3f300000.mmc/mmc_host/mmc1/mmc1:0001/mmc1:0001:1/net/mon0, iface: mon0): no ifupdown configuration found.

It’s as if the operating system froze for some reason and suddenly got back working 5 days later! Absolutely no reboot registered.

I have absolutely no other log.

Does anyone know what could have happened there?

Hi OmahaWiz,

Welcome to our forums.

Strange issue. Sleep mode maybe? There isn’t any much more explanation on the magical “come alive by itself” feature apart from that. To verify, you can query your network interface with iw:

$ sudo iw dev wlp3s0 get power_save

You’ll need to replace your network interface in the above example. My output shows that I do have power save mode on:

Power save: on