Reboots or Restarts but no Logs

I currently have the problem that my home assistant installation on the Raspberry pi seems to restart frequently Probably (every hour or so).

This is particularly annoying because Tailscale is now also running on it and so there is no internet available for my clients.

the problem existed from the beginning (before most addons were installed and even ZHA was used instead of Z2MQTT), but it was less of a problem because after a few seconds access to the dashboard was possible anyway and the cards displayed values again after a short time.

but now i have the problem that i can’t see what causes the reboots or the restart of HA (i am not even sure if the whole OS or only the HA Services restarts), because the logs seem to be deleted automatically with every restart. does anyone have any ideas?

there should be a log file in the config directory named something like homeassistant.log.1
the .1 log is the log from the previous run of HA.