How to choose the right technical characteristics of the server for the tasks of the WEB server?

Question

Server equipment

Now we have 75 users, everything revolves on the server (Debian), which was not assembled by me on the "knee" about 5 - 6 years ago, + ISPmanager.
There is a question of expansion, since the number of users will increase to ~ 180 - 200 in the near future. All budget employees. Each user has a flooded site, purely nominally. Not many site visits.
The essence of the question from the title: Which server characteristics to choose?
The main task is WEB server, hosting. Budget up to 100 thousand rubles.
There are many solutions on the Internet, but my problem is that I still cannot understand the need for this or that option when configuring the server for tasks. Which processor to choose, how much RAM will be enough, well, etc.
Thank you all in advance for your replies!

Answer 1

Ummm ... I will probably answer with a finger to the sky, but maybe update what is. In fact, I have 4GB frames and 2 cores pulling 267 connections and 2 sites, but of course I will change at least I3 8GB frames.