503 issue on website

Hi all, i have a very common problem i cannot seem to resolve.
My website returns a 503 error.

I have a wordpress 5.3 (latest version) on my webhost running:
OS‪CentOS 6.10 (Final)‬ProductPlesk Obsidian
Version 18.0.23, last updated on Jan 22, 2020 02:33 PM

Things i have tried to resolve the issue:

Wordpress (no results)

• Disable all wordpress plugins
• Enable all plugins
• Change theme without plugins
• Change theme wih all plugins
• Suspend the website (resolved the...

503 issue on website