HA OS crashing

Since sone days my home assistant os is crashing every 2-3 days. It was running for 5month on a Raspery Pi 5 on a NVMe Disk without any problems.
It seems the hardware is still running, I can ping the ip. But the docker containers are not running.
Where are the logs to see the errors?
After a reboot it is running well again.
Thanks
Lukas

See number 4 & 5 here:

How to Troubleshoot Raspberry Pi Crashing.