Transmission slows down all internet surfing for the network

[Jakobud]

I'm running Transmission on a Ubuntu server on my home network. I have 3 other computers connected to the network.

When Transmission is downloading something, even if its only downloading at 25 K/sec, internet surfing traffic slows to a complete crawl, even though I have a 6 megabit/sec cable connection. Speedtests even show me getting 8-10 megabits sometimes.

At the moment for example, transmission is only downloading one thing at a speed of 25.1 K/sec, using 14 of 20 connections. And internet traffic for every other computer is super slow. When I pause the torrent download, everything is back to full speed.

My peer-limit-global is 80, peer-limit-per-torrent is 60.

Is 14 connections really too much for my router to handle? It's a Linksys WRT54G running DD-WRT. Seems like in the past when I ran uTorrent on my desktop I could have over 14 connections without issue...

Do other people experience similar slowdowns as this? Where does the issue lie? Obviously Transmission is not eating up too much bandwidth (only 25 K out of available 6+ megabits)...

[Jakobud]

Very interesting site. Thanks for the link!

[jch]

Try 8 connections.

Em, no. Jakobud's router is running DD-WRT, not the original firmware; DD-WRT on a machine with 16 MB of RAM should be fine for thousands of connections. (To make sure, please log into the DD-WRT box, and type "logread | more" -- there should be no scary-looking warnings.)

I can see two reasons for that. First, Jakobud is not telling us what is behind the DD-WRT box, probably an ADSL or cable modem. This box could be the one being overwhelmed by Transmission's traffic, especially if it is in "NAT" or "router" mode, as opposed to "bridge" mode.

Second, it could be your ISP detecting that you're running BitTorrent and throttling you. If so, please write an angry letter to let them know that they're losing customers that way, and change ISPs.

--jch

[Nonja]

limit your upload speed to a 10-15kb/s upload cap as a test.. you're probably choking that out.

...simple, but generally overlooked

[jch]

Just to clarify. Smallnetbuilder gives [DD-WRT on this router] a rating of 60 max simultaneous connections.

That's really disappointing. Thanks for the correction.

--jch

[Chindokae]

I had exactly the same problem here, but I fixed it.

If the router's firmware can handle 60 conns but it is having trouble at 14, then maybe you are looking in the wrong direction.

I found that my ISP had begun employing traffic shaping when it saw a certain number of upload connections. The Transmission client is hard-coded to have at least 14 upload slots. The ISP's know this. I have found that by reducing the number of upload slots to 10 the problem just went away. I didn't have to reduce my upload bandwidth at all, in fact I upped it by 150K.

You can't specify the number of upload slots because the developers have very unhelpfully coded the client to rewrite that setting in settings.json (upload-slots-per-torrent) to 14 at startup. You have to change the setting in the source code and build the client yourself to get around that problem.

I have asked them to change this, but if they insist on mandating this setting, you might try qBittorrent. It allows you to manage that setting and many more.

[Longinus00]

Don't edit settings.json while transmission is running.

[eden6000]

Same for me, Lucid + transmission 1.92...I've tried many combinations, many settings, I've come to the conclusion that it's not related to the router (I've tried 2), nor the wireless or wired connections (it has the same behaviour), and what I don't understand is that the same transmission 1.92 under Puppylinux works fine! But, in my searches, I've found something that I hope can be useful: as I said there is no changes in limiting for example the bandwidth (apart from the obvious fact that if you use ALL your bandwidth, it's difficult to also surf the internet...), since if there are more torrents running with a total of 10-20 kbs (that is nothing), this is enough to stop all other connections...BUT if you pause all torrents except one, no matter what, even if it goes at full speed, everythings restarts working...So, for me, there is something related to the concurrency of more than one torrent running, AND in conjunction with a specific os (Ubuntu in this case)..maybe someone else could try this?

[Macuserman]

Hey guys !

I'm a french user, so I apologize whether my english could be wrong.
I've a really like-it problem.

I've got a Mac with 4 gigs of RAM, an wireless internet connection which works great. In fact, I used to have.
I explain myself:

I have a Mac running OS X 10.6.3, and Transmission 1.93 (last one, whatever…), 4 gigs of RAM and a 8/10 Mbps internet connection.
When I launch Transmission, nothing "paranormal", it just works. I've got, when I download, a cabled connection. But it does not go over 30 kbps…
When I turn the WiFi on, it goes suddenly to 300kbps (I asked the soft no to go over this limit…) and then, about 10 minutes later, it goes straight to 0kbps. Impossible to go over again. When I try to google something, impossible. Internet is not slow, there's no internet at all ! I can't google, download or check my email…

And when I'm on, with the cable, I does not go over 40kbps, never. It isn't stuck at 40 kpbs, but, it goes like this: 12, 17, 11, 24, 32, 6, 3, 0.7, 4, 6, 28 etc…
And that with 4, 7 or even 21 sources (seeders…).

So what's wrong ? Please help !

Thanks a lot !