Seeing you're still active here - did you got your unit working by now?
Hi, no, I haven't found a solution yet. The crashes are intermittent and difficult to reproduce, sometimes occurring after more than 20 days, which makes troubleshooting very time-consuming. Since replacing the power supply, the frequency of crashes seems to have decreased, now happening roughly every 15 to 30 days. I had previously tested the RAM for a few hours without any issues.
However, after seeing your post, I ran a more extensive Memtest overnight for about 10 hours, which initially showed no errors. Unfortunately, the system eventually rebooted during the test

. I'll try testing with a different power supply to see if that makes a difference

.
For what it's worth, I've seen similar crashes on various forums.
Some users resolved their issues by replacing their power supply (
link), while others have suggested potential incompatibilities with I226 network chips and MTU settings (
link).
If you're encountering errors during Memtest, it might be worth trying a single 16GB RAM module, as the processor specifications indicate a maximum supported memory of 16GB (
link).
Additionally, if you have the fan connected to the PC's USB port, try powering it with an external power adapter. I was able to run Memtest for more than 24 hours without errors or restarts. This makes me think that one cause of the instability could be the continuous power draw from the USB port by the peripherals. We'll see over time if it crashes again.