Website down. And we don't know why

Job ID: 37428208

Budget: €30 – €250 EUR

We have a Wordpress Website running under Plesk on a Ubuntu Server running on Amazon Lightsail.

The Website is keep getting offline.
We already createt a new instance under Amazon Lightsail from an old Snapshot that was working fine but still getting same error.
Website is online for a short time but then getting offline again?
DDos Attack?

Need urgend help!
Related categories: PHP Linux Web Security WordPress Amazon Web Services