zerflin I have double checked and ran tests, the link I provided says how to fix. Wordpress by default and most plugins don't actually use the real users IP but only the one making the request, and in most cases this is a proxy like CloudFlare or our own internal Nginx proxy.
By adding the code on that page it will replace the IP string with the real user IP behind a proxy. One note is we do auto block wordpress logins after a few failed attempts per unque IP and we do look at the origin IP. As a result bots switch IP's like candy and we see usually a few hundred per day making attempts.
The list you are seeing in reality are more then likely all different real IP's and we have blocked most of them and the only reason you see more all the time is that the plugin does not show the real IP and just our server IP in it's place.
I am sorry it's complicated I have been hoping for years that wordpress would make the changes as almost all modern hosts use a reverse proxy like Nginx or Varnish in front of the web requests to PHP.