Using a bittorrent client slows down internet connection

I have a problem while using transmission. I don't know where it comes from because it doesn't occur every time.

Sometime while downloading a torrent, I cannot browse on the internet with a browser. Or if I can it is extremly slow.

I opened the correct port on my router. I limited the upload download to a reasonable amount (50/5, my upload is very bad). I don't not allow transmission to use PnP and NAT-PMP. And this doen't seem to be related to the download speed of a particular torrent: before limiting download I could download at 800ko/s and have no problem and sometime the problems occurs with download at 3ko/s.

Is anyone else having this problem?

I really don't understand, isn't opening the correct port and disabling plug n play suppose to make transmission not interfere with http?


Solution 1:

The problem, in your case, is probably not the data rate but the number of connections. Many internet gateways can't handle many connections at the same time.

You can Limit your maximum amount of simultaneous connections in the Transmission preferences like so:

Preferences → Network → Maximum Peers per torrent

Try to keep these values very low at first. 5/10 is a good starting point. And increase them slowly as you find it working.

  • Note: Especially new torrents can show this behaviour. If you wait until there are enough seeders for a torrent, it'll be slowing down your browsing much less.

  • Note also: You shouldn't have to limit bandwidth. This is handled by the TCP/IP stack, no problem, in most cases. It tries to schedule packet delivery fairly.

Solution 2:

Set your upload to 50% of your max upload bandwidth. You can have the download unlimited or limited. I set my download to 90% of max.

I have found with bandwidth saturating programs (Torrents), if the upload gets to > 75% of your max outbound limit, it severely hobbles all the data transfers on the system (Browsing). TCP/IP is a two way street, the packet replies have to get back to the sender before they can send another packet.