What is the right way to set up the work of clients and their sites in my situation?

Question

Server equipment

Good afternoon, dear, for 6 years now, the question has been brewing for me, how can I put my work in the right way.

The situation is as follows, at the moment I have more than 15 clients and each has 1-3 sites. There are 1000 hosts per day, and there are up to 10.

+ Own site to attract customers.

And all sites are scattered across different hosters, and sometimes sites are in one place and domains are in another. There is also a clumsily configured VPS and 10 sites hang there. The memory load is 95 percent, maybe due to the fact that I am such a system administrator. And it happens when on some site they start to guess passwords, or some kind of scanner, in general, all 10 sites fall.

There is also a problem with tracking when and where you need to pay for the domain to either SSL or hosting.

Well, in general, you understand the essence of the issue, tell me who does what, so that it is convenient to administer, but the back was also covered in the form of backups, and so on.

I thought to take a more powerful server, put ISPmanager Busines there and act as a host for my clients, but there are 2 problems. 1 All the same, here you need to configure everything normally, and the second is the cost of the server for ISPmanager Busines, where the requirements are strong.

Thanks for answers.