This problem is a bit strange, and I have no idea where to start debugging this. Allow me to explain the situation:
Hass.io is working great - no problems whatsoever. SSH, let’s encrypt, duckdns, zwave and mqtt for presence detection. All is working fine.
However, as far as I can tell, everything “breaks” randomly: once every few weeks I loose access to ssh and the webinterface. SSH tells me the connection is refused, and the webinterface URL gives me the page as if the server was down. Additionally MQTT does not accept anything. BUT, my Pi does still have internet access, because automated tasks that send out emails (using mailgun), and controls my smart devices (local network), still work. So there still is some internet access.
So it seems as if all incoming connections are blocked, but all outgoing connections still work. It’s really weird.
Since I can not access the pi using SSH or the webinterface, all I can do is pull the plug to shut it off.
After powering it back on again, everything runs great again.
But pulling the plug is terrible, I already corrupted an SD card once, and would like to avoid it in the future. But at these moments there is just no other way.
Does this sound familiar to anyone? Or could anyone tell me how to locate and solve this problem?
(It does not appear to be HASS related, because it happened on a bunch of different versions, I am now running the latest one using the build-in updater)