Hi everyone,
I just wanted to share an update because I believe I have found the root cause of this issue.
After checking my klippy.log, I noticed that right before the freeze there is a long sequence of nulnulnulnul... and then the log suddenly stops. After that, the whole system resets. This confirms that the SBC is crashing, not just Klipper.
I followed the troubleshooting steps from this post:
https://klipper.discourse.group/t/help-klipper-crashes-mid-print/24434/44
After applying those changes and fixing the root cause, my printer has now been running continuously for 4 days without any freezes, disconnects, or crashes.
KlipperScreen remains responsive and Mainsail stays connected the entire time.
So in my case, the issue was not a Klipper configuration problem, but a system-level crash on the host.
Hopefully this helps anyone else who is seeing random freezes with an unresponsive screen and no web access.