The upload speed on port 80 and 443 is very different, why?

Question

Server equipment

Hello.
Sorry in advance if the question is too broad. It just might be that someone else has been in a similar situation.
"Problem" in what, I can not understand the reason of such behavior. I'm testing DO servers from different regions (Netherlands, Germany, England), in general, any EU servers - in order to upload a file to them. On the test server, nginx is installed and an HTTP POST request with a file is simply thrown, then the speed is looked at.
On the standard port 80, the speed to such servers always seems to be limited to 8 Mbps.
On a secure port 443 (and https), the speed is surprisingly kept at 100 Mbps (the maximum of my Internet).
Bonus: over SSH (standard 22) the speed is 30 Mbps.
How to understand what could be causing this behavior? Contact a provider?
Internet Dom.ru. I'm testing from Windows 8.1, antiviruses and firewalls are disabled, connecting the cable directly to the computer - there is no router.

Answer 1

Rather, all this is a problem on the side of your provider, very often they listen to unprotected traffic, of course, the speed slows down. I don't see any other reason. If possible, check with another provider in your area.

Answer 2

I'll subscribe, although there was a similar garbage, though with a VPN, the fault of the DPI (obliquely tuned) on the provider's side, if you try the same thing on another wire?