What is the reason for bad internet?

Question

Computer networks

In general, the scheme is such a single-port ethernet + adsl2 + modem, it is connected to another conventional 4-port ethernet + wifi router to which a PC and an IP-TV set-top box are connected. Internet resources were loaded with a delay when the torrent client was on, which did not download anything (and only after it was turned off it worked better), after replacing the above-mentioned modem and router with a 4-port adsl2 ++ wifi router, the Internet is loaded in normal mode even when the set-top box is running (although this did not affect the 1st configuration either) the speed was 10-12 megabits / s or 1.4 megabytes / second, TV in SD quality ate about 300 kilobytes / second. What is the reason?
PS probably the reason lies in the number of actual TCP connections on a single-port modem that open when the torrent client is running, which may be a limited number

Answer 1

adsl modem, read here
And we delve into the essence:
ADSL provides .... the speed of the "upstream" data stream from 640 Kbps to 1.5 Mbps.
If you have a lot of connections outside, then you probably clog the 1.5 Mbit channel OUTCOMING FROM YOU by at least a quarter, and these are already problems for packets.
The more outgoing traffic with ADSL, the lower the incoming. This is not an asynchronous transfer in the correct sense. This is pre-async.
In your case, the less you have a torrent on the distribution, the greater the incoming speed.