Hi,
From the log, a large number of desktop-related errors were reported before the restart.
That log does not help. There are 3 mins gap between the desktop-nm and reboot. I don’t think it is the cause.
Actually, your syslog is full of the nm-applet log and it has been printed for 4 hours before the reboot.
Jul 28 04:09:23 nvidia-desktop nm-applet[7151]: Can't set a parent on widget which has a parent
\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00Jul 28 04:12:37 nvidia-desktop systemd-modules-load[2209]: Inserted module 'bluedroid_pm'
Jul 28 04:12:37 nvidia-desktop systemd-modules-load[2209]: Module 'nvhost_vi' is builtin
Jul 28 04:12:37 nvidia-desktop systemd-modules-load[2209]: Inserted module 'nvgpu'
I don’t think this description really helps. We need the log to tell what issue happens but not just descriptions.
No need to mention you didn’t tell us what is your carrier board or release version.
Please do dump the log from serial console when error happens and attach it here. If you cannot reproduce it now, then you should firstly reproduce it and then come to forum for help.
Also, you should tell other people what is running on the board. If you provide more info, it has more chance to resolve your problem.