Do cabled connections and Wi-Fi "use" the same bandwidth?

My brother likes to play games online on his Xbox. However, because he is far away from the router, he uses our Wi-Fi instead of an Ethernet cable. I, being closer to the router, use an Ethernet cable for my desktop. Occasional I torrent/seed Linux distributions, which takes up a large portion of the available bandwidth. Are the two methods of obtaining access to the Internet separated?

That is, will downloading a large file on my computer affect my brother's available bandwidth despite the fact that I am using an Ethernet cable and he is using the Wi-Fi? My intuition says yes, as both methods have to go through the router, though I could be wrong as my background in networking is lacking to say the least.

7 Answers

To borrow from U.S. Senator Ted Stevens, the Internet is a series of tubes. You have one tube coming into your house—the ISP connection plugged into your router.

Everything behind your router shares that tube—think of the Ethernet cables as a regular straw, and the Wi-Fi as a long, flexible straw. If someone on the Ethernet straw is drinking up all the bandwidth there's none left for the thirsty person on the Wi-Fi straw.

Additionally to what has already been said:

Downloading a large file does not directly influence bandwidth. As long as the file is being downloaded slowly, its size does not matter.

You also mentioned torrents. Torrents have a very interesting effect on networks.

1. downloading a torrent may significantly degrade your internet connection quality or that of other people sharing the same connection, including bandwidth and/or ping even without hogging the network's entire bandwidth.
   By opening a large number of concurrent connections, a torrent can overload the processor of your router, which translates into a huge drop in overall networking performance (and even overheating in the worst case).

2. uploading (seeding) a torrent can have the same effect as downloading one, but for a different reason.
   A connection can only be established, when a client (you) makes a request to a server (upload a message). The server responds with some data (download), but since anything could happen to the data along the way, such as packet loss, the client needs to verify the data's integrity and report back to the server, either with an "I got the package, please send the rest", or with a "the package's corrupted, please send again".
   If you're already using your entire upstream bandwidth for seeding, your or other computer on the same network may not have the necessary bandwidth for base communication.

Torrents do not have to be a networking dead-weight, as long as the torrent client is configured properly. Limit the maximum amount of connections to a reasonable value, and do not allow your client to use up the entire network's upstream.
There are plenty of good guides online for configuring a torrent client properly.

Yes, both methods consume the uplink bandwidth to your ISP. All traffic on your network that transits the router (downloads, video streaming, etc., etc.) shares the internet connection bandwidth.

1. A wired connection has the capability to use more bandwidth than the wifi and will win in any speed race.

2. Most of the answers and comments are all correct, but I want to mention you can influence who gets priority over the bandwidth by properly configuring your Quality of Service (QoS) settings. The way to do this is different from setup to setup (its going to take some time to figure out and the router is the key player on this) and there are guides online geared towards Xbox optimization. In theory, properly configured QoS can help you get maximum utilization of your bandwidth while reducing compromise. (Also it is better, or critical even, to play online games with an Ethernet connection, and one with the highest setting allowed (Test it out!)...it responds faster...lower latency)

Here is an excerpt from the web:

"If you're using your 360 and you start having latency issues, especially when others are using the same connection as you at the same time, then you should look into using Quality of Service (QoS) to prioritize your 360's traffic above other traffic."

Note: I think MaQleoud is confusing internet bandwidth with the router's hardware load. Wireless is a more complex way to communicate and can potentially use up more of the router's hardware capacity. Some routers have really crappy processors, buffers, etc.

It will affect the bandwidth your brother has available. However, online games are not THAT bandwidth intensive. To give an example: I play several MMOs, and on one of them, playing with a group of 24 other players takes less than 10 Kbps during the most intensive moments. Most other games are in that same ballpark.

That doesn't mean you shouldn't take precautions against bandwidth overconsumption. I don't know how much bandwidth you have available and what your download cap is, but as Nolonar mentioned, make sure you have your torrent setup properly.

Problem is that your seeding creates a lot of connections to other down-loaders, therefore PING increases a lot. If you have to play FPS games, 50-100 ms can hurt much.

Try configuring QoS in your router, limit torrent upload speed and connection count limit.

I know nothing from a technical IT perspective. But I am sitting on an Apple iMac retina with a wifi connection.

In the adjoining room, my sister has an ancient computer running Windows XP with a LAN cable, right next to the modem/router.

We share one ADSL connection.

Whenever she is on the computer, my internet speed drops to practically zero. I can't do anything at all.

I don't know what all that is about, but I am so frustrated by not being able to do real work while she is running nothing more than facebook, well I am inclined to adjust the QoS settings on her computer to see if that makes a difference.

Even when she uses another wifi computer, she's definitely getting more things done. So from experience, something is going on and the bandwidth is most definitely not being shared equally between these two computers. :(