Dedicated server management

Description

We have a new dedicated server which has been running for a couple of months.It is a AX42 Dedicated Server hosted at Hetzner 2 x 1 TB NVMe SSD It runs on cpanel
We have been finding that it crashes occasionally, and we cant work out what is causing it.
The server hosts around 20 wordpress sites (3 large, the rest are small), it is likely one of the plugins.
We use freshping to monitor a couple of the sites and can see that they all go down for a few minutes, then come back up again.
We would like someone with related experience to validate the server setup, optomise it where necessary and find the source of the error which is causing it to go down when it happens.
Something that may be related, when we try a product catalog export from Woocommerce on one of the sites it gets stuck and wont complete. It can export sections of the product database up to around 110mb, but not the full file which is around 190mb.
We are also having trouble connecting via FTP at the moment.
If you are experienced in server management please place your bid, to include finding the fault causing the sites to go down and resolving it. Also to include resolving the woocommerce product catalog export issue and connecting via FTP.
We would be looking to build a good relationship with someone with fantastic experience and excellent problem solving capabilities that we can do further projects in the future.