Have been struggling a lot with unreliable WiFi and more recently not being able to reconnect to router even after rebooting. Since the Octopi runs purely in headless mode I always suspected WiFi signal strength issues to be the cause for OctoPi going off my network and not being able to reconnect.
This is after trying to resolve signal coverage and strength issues by getting a signal extender which improved coverage and signal quality.
Connected to a monitor to troubleshoot.
Got a warning
fsck: Warning... fsck.vfat for device /dev/mmcblk0p1 exited with signal 6. fsck died with exit status 8
Went into a rabbit hole of googling sd card errors and recovery procedures till I came across a forum posting where someone just mounted the sdcard on a windows machine and fixed the problem automagically. Guess what I do have a Win 8.1 machine. No harm in trying. As soon as the sd card was mounted windows detected that there was something wrong with it and graciously offered to fix it. Took the fixed card back to RPi and waited with a bated breath for it to boot up. To my surprise it booted up perfectly with no errors. So here is another anecdotal evidence supporting the automagical sd card healing properties of Windows.
But the elation was short lived. Got the omnius Rainbow Square on top right. Not steady but pulsating.
The warnings could be triggered both by power supply and usb cable.
So if you are running headless (which is usual with Octoprint) you have no way of knowing about the under voltage issue. Mike Redrobe has a solution to monitor this remotely.
I am suspecting the microUSB cable (microcenter) which works well for charging my umpteen other devices but somehow fails here. The only other device connected is the Edimax wireless dongle and RaspberryPi Camera.