The USB HDD speed has dropped, what is the reason?

Question

linux

I don't know, help me, no, but we'll try.
There is such a disk, Free Agent Go 500GB Seagate without the possibility of connecting additional power. All this is connected to the single-board Radxa Rock in order to create a local NAS, download torrents and a small web server. Problems began immediately, the HDD began to turn off. After some time, I realized that the board simply did not have enough power. And so that the power went on, I made some kind of system. I cut the HDD to the board and add. I connected the power wire coming from the USB tip to a two-ampere telephone charger. It turned out the following Open photo. The wire that lies on the router is connected to a white USB extension cable that connects to the charger. That's all. The problem was solved and the disk did not turn off, but after 2 months I started copying the file using Midnight Commander and saw that instead of 30MB per second, the speed dropped to 9MB per second. Tried to connect another drive, same thing. I came to give the board a rest, but after turning it on for 10 minutes, the speed is 40mb per second, and then drops sharply again. I tried to connect to another USB port, it did not work. Has anyone encountered this problem and knows how to solve it?
Update #1
Tried to fix bugs. The speed of data exchange with any USB devices is not more than 20 MB per second.

Answer 1

Counter question: are you sure that you write in Russian at all?