I have had it a few times too, both red and green. This bug has been reported to together.jolla.com, at least twice:

https://together.jolla.com/question/...-phone-yammed/

and

https://together.jolla.com/question/...ly-shuts-down/


In the second thread there was a message someone had gotten from Jolla care:

"We are sorry to hear about your continued problems with your Jolla phone. We have the following two options to offer:

1) Wait till the next SailfishOS update - planned to week 10. It will contain a fix for the phone-turn-off-by-itself issue.

2) Send your phone to service (we would tell you how).

Please let us know which option you want to take.

Sincerely, Jolla Customer Care"

So hopefully it will be taken care of in a few weeks.

Today it was different.
Awoke the display on by hitting the power button, phone unresponsive for long seconds, usual connection problem (why the heck it has to freeze the WHOLE UI!), then display went off, quickly blinking red light.
I thought it froze and was about to remove battery, when it (after few seconds of red blinking) switched to quick green flashing for a second or so and I was able to unlock and use the phone.

I think it crashed (WiFi module may be, but not so bad to kernel panic), the red blinking is probably a memory dump and the green one means he's sort of recovering.

There is also https://together.jolla.com/question/...-phone-yammed/ .

But what anidel describes accurately matches what's happening to me too!

Thanks Javi, your first link was also quoted above, anyway

I don't mind the reset or crash (well, I do), but I mind A LOT MORE that the UI freezes because of network issues.

It shouldn't.

Joining in as I had the same behaviour a few times. To recover I had to restart by long press of power button. I will go and vote on the bugs.

That network error is annoying though. Sometimes I got it to stop when switching to aeroplane mode and back.