Set up Ubuntu 16.04 after the initial installation.

Good day everyone. We have a dedicated server AX41-1-LTD at Hetzner. Specifications: AMD Ryzen™ 5 3600 Hexa-Core "Matisse" (Zen2) 64 GB DDR4 RAM 2 x 512 GB NVMe SSD (Software-RAID 1) 1 Gbit/s bandwidth We use FASTPANEL as the control panel for the websites. In the last 5-6 months, we have encountered a problem with the low performance of one of the websites on the server. The site is on WordPress. The size of the site is 56 GB. The size of the database is 15 GB. There are 33,000 products on the site. A "Regional Structure" has also been implemented. In our opinion, this heavily loads the hardware, as when editing products or working with the admin panel, a 504 error almost always occurs, BUT at the same time, the CPU load has never exceeded 25%, and the RAM operates at 3-5 GB out of 64 GB. Additionally, the Hotline service systematically cannot recognize the feed, which also constantly returns a 504 error. A set of tasks needs to be performed to improve the performance of this site. - Change resources for PHP. - Analyze traffic from spam bots. - Analyze what and in what quantities is causing the maximum load on the server. And possibly other tasks that will allow us to fully utilize the server's power.