Restrict traffic on a specific port?

Question

Shaping

Good afternoon. Available:

• home network
  
• router Asus rt-n56u with firmware from Padawan
  
• slow ADSL internet
  
• neighbors who like to download torrents without limits
  
• neighbors are included in a separate port in the router (they have their own wifi point there, so only one port needs to be limited)
  

At first I thought about the shaper (on tc), and even the router seems to have such a command by default, but I didn’t figure it out with the manuals. It's all very complicated. And besides, you need to disable the hw_nat module, which will affect performance.
Then, poking around in the new firmware, I came across setting up LAN interfaces separately. I put 10mbit/half duplex on the port, however, people began to complain that there was no network at all. Probably, half duplex affects. On 10mbit/full duplex everything is fine, but the speed is higher than the provided internet.
Then the idea came up, what if on some machine (even on a router), generate traffic through this interface. And the amount of this traffic to limit them to the Internet. Those. We drive 8 Mbps to their router through this interface, and only 2 Mbps remains for the Internet, which is normal.
Tell me how you can generate such traffic without a heavy load on the computer, will it help. And are there other convenient ways to limit their traffic? QoS somehow does not really affect the situation.
PS Go and negotiate with the neighbors is not an option. They say they don't pump. Perhaps this is true, and there, in fact, a botnet is operating, but in any case, you need to limit traffic.

Answer 1

Putting something else on the way to the neighbors - do not consider at all?

Answer 2

I give up. It's not L2. Was wrong.

Answer 3

You are correctly advised in the comments - to buy a cheap piece of hardware (Intel Atom or VIA C3 will be enough), install Linux and shape traffic through the tc utility.

Answer 4

I would buy a normal device, expenses at the expense of neighbors, and if they are indignant, let them connect themselves.

Answer 5

If the Asus port to the neighbors has a separate IP interface, then you can go to Asus via Putty-nd and set the speed limit via tc:
habrahabr.ru/post/119611/
Then you need to make sure that they are loaded when Asus is turned on.
It already depends on the features of the firmware.
In normal Linux, it is customary to use /etc/rc.local