Not sure if this category is correct but I need a watchdog that can restart my rpi4 with home assistant os of the system crashed. Maybe by switching a power plug off and on. How did you guys solve this? Any recommendations?
If the system crashed, its not reachable nor functional anymore. What will a watchdog then do? Think about it…
If you mean if the process of “HA” is not running anymore, you can check that for example if you have a defunct and if so, restart the service. Or you could check via a cronjob if the socket is still open, if not reload HA.
As I am not familiar with this setup, I cannot tell you details.
Coming back to your “system crashed”. If the system crashed, like already mentioned its not responding to anything. For this you might need another system to check if the system is reachable or not, if not… surely you can use a remote controlled power socket…
As you see there are different ways and approaches… and there a lots more. So the better you describe your issue or use case, the better the answer will be…