How to increase download speed?

Question

Mikrotik

Hello,
There is a problem in the network with downloading content from the Internet, and at some time, for example, a 200-250 MB file is downloaded quickly, but this is rare, often the download speed does not exceed 80-100 Kb / s and it does not matter via Wi-Fi or network diagram I test the speed with the

iperf utility from one computer to another over the wire

I do tracert to Yandex
tracert from computer to computer from different vlans
Loading by interfaces

The channel loading is low, even at the time of downloading the file, neither local interface nor wan interface
Browsing speed over the pages are good, I would say excellent, in YouTube the video loads perfectly, without delay, but downloading the file is just disgusting, I don’t know where to look, please help.
If you directly connect the provider to the laptop, then the speed is good, the files are downloaded quickly, that's all ..... it's a matter of the network device
Loading the interface when downloading a file of 120 MB

and during normal loading, on the port of the router, the speed on the interface shows 10 Mbps .

Answer 1

in YouTube, the video loads perfectly, without delay, but downloading the file is just disgusting, I don’t know where to look, I ask for help.

Maybe the problem is not with you, but on the server from where you download the file?

Answer 2

All diagnostics should be carried out at the time of the problem. If it can be called artificially (i.e., for example, braking is sure to appear on one of 10 files), then half the work can be said to be done.
As soon as the problem arose.
1) We check the load on the ports
2) We try to create an additional load, see if it was possible (you can enable 4k video on youtube from another computer in the same vlan)
3) We try to create a load from another vlan.
4) If the utilization of the channel grows with the increase in load, the load successfully "scales", then we try to download a file of a similar format from another server (at the time of the problem) in the same vlan. (The file format can affect the operation of antiviruses)
5) Repeat step 4 on the computer that has a problem (there is right now).
If all 5 points show normal operation, then the problem is in the channel between you and the server (including the problem may be with the server itself).
In any case, this will allow you to cut off a bunch of options.

Answer 3

Well run on some external server in the internet iperf. Check in udp, tcp mode. The scheme is too nontrivial. It may turn out that the jamb is only on tcp and the problem is in some mss, or maybe in a curve balancing between providers. Or maybe the cant is on both udp and tcp, then you need to look at problems at a lower level - on IP, here it can be trite losses, or maybe excessive fragmentation, or maybe the router is overloaded by the CPU in small packets.
maybe, yes, there can be a lot of things here ... Run iperf on an external server and smoke the output. bwping is still worth a try, but iperf is more reliable