My site has done that twice in the past week but it fixed itself within 5 minutes each time without me having to reboot the server.
It’s been down three hours already.
Wow it seems its something more serious. I would check your error logs for clues.
I would but I don’t know where to look. I did the server audit and found this.
2265BC9B-7D2D-4820-8F9B-E12C04D6E5E4.png