I have two RPi's, one 3B+ and one 4 8GB. Both run updated Raspbian with Node-Red, VNCServer, No-ip DUC and have SSH enabled. No mouse or display connected to any of them. The 3B+ serves as the "sensor grid" and the 4 runs a GUI and statistics collecting data through API calls via Node-Red.
The 3B+ has previously been running fine and I then used IBM Cloud Node-Red for GUI but bought a 4 to run the GUI this June.
Since the "refresh" of the system something has clearly happened as the both of them "freezes" and stops operating. It happens once or twice a day and after restart all runs fine and I can't detect any high CPU or memory leak or something "obvious".
The "freezing" means that they are completely dead but not completely crashed as often the VNC connects but it says that there is no desktop running. Also I sometimes get the SSH connection (login) but then the terminal isn't responding to any commands.
How can I try and figure out why they both are acting this way? Which logs or what to check?
SD card would of course be an obvious place to start but I already changed SD in the 4 and that both SD cards would give up at the same time feels too much of a coincident...
Any pointers in where to start looking?
EDIT:
I found an older backup (about a year ago) of the SD card for the 3B+
that I restored from and now it is stable!
I've set a timer that will cut power to the 4
which cuts power off/on for 15 minutes each night and then it runs fine for 24 hrs...
dpkg --list
(of course filtered with a script). – Ingo Jul 26 '20 at 09:33