Slow speed in Debian?

Question

Debian

Good afternoon, colleagues!
Faced a very high problem. I will explain perfectly!
I have one physical server and raise two virtual servers on it. One of them serve as NAT and is up on Debiane. This VM has a speed issue. After installing an SSL certificate on the NGINX Web server, the speed completely dropped to almost kb / s. I installed speedtest-cli on the server and checked it naturally like this. Checked the speed on the second virtual machine. The speed is almost 100 Mb/s Colleagues, please advise how to check where there might be a problem in the Debian server? How to check? Check what ?
On the first server, there is a public IP that Nat provides to serve for the site and of course the site opens like a turtle (((

Answer 1

Colleagues finally found the cause of the malfunctions. The problem was that there was a shaper for white IP addresses from the outside. We got to the site by DNS address very slowly. NGINX up on this server. HE redirected requests to another web server. Thought at the beginning with NGINX the problem, long agony found the cause. Attached screenshot

Answer 2

Knowing how in Tashkent with data centers and the Internet in general, I would try to kick the hoster (after standard OS diagnostics, of course). There is no certificate here.
Speedtests are not indicative for the same reason - the channel to one operator can be fast, to another (and, apparently, your site opens through it) - much slower.

Answer 3

Nat is provided where? If you have debian looking out into the world, is the firewall configured? Do you happen to see a crowd of bots there? Is there a DNS server there? Is access to it from outside closed?