Sometimes, my router (RB751U-2HnD) reboots automaticatly, for example, tonight with 10 days up, but sometimes, 2 or 3 times in a day. Just the router......

What logs do I need to keep in the "disk" for discovering or trying to discover the issue?

Thank you

Hi,

reboots may occure if watchdog triggers.
One possible reason for this is (very) high CPU load.

To find the reason, I suggest you configure the "error", "warning" and "critical" topics to be logged on disk.
Another way is to use a syslog server to collect the log messages (personally I prefer this way).

Ape

also check your power supply. i had random reboots with another brand psu in my rb951ui