complete freeze when using any torrent client

[Idonteven]

Hello everyone;

I'm new here and I have registered because I have two major problems that happen every time I use a torrent client. I was wondering if anyone could tell me why this is happening, and help me figure out how to make it stop. I'll try to give as much information as I can.

First, I will point out that this only started happening after I moved, back in October, and had to change my internet company. I am now using a wireless wi-fi device to connect to the internet (photo of the device:)

So, as I said, two problems. The first, ( also the least serious out of the two): whenever I use a torrent client, (I tried many), my internet browser stops functioning. As a result, I can not download torrents and surf the internet at the same time, because if anything is downloading, all I can get from my browser are “not found” error pages. This is not a problem with the connection; the torrents are downloading normally and at a decent speed . But whether it's Opera, Firefox, Internet Explorer, or any other browser, it will simply act as if I wasn't connected to the internet. The only way to make it work again is to restart the computer. Very annoying!

Note that, on occasion, it continues to work as normal. I have no idea why it usually stops working but not always. And, for some reason, Internet Explorer doesn't seem to fail as much as the others.

If that was the only problem, I could live with it. Problem number 2, however, is more serious.

Whenever I use a torrent client, after a while, the computer will freeze completely. The screen becomes completely frozen, and even the mouse cursor will not move. This happens no matter what I'm doing, whether I'm watching a video, playing a game, etc. If there's any sound playing at the moment when it freezes, the sound will also get stuck; for example, “Luke, I am your fatheEEEEEEEEEEEEEEEEEE”.

The only way for it to get un-stuck is for me to manually switch off the computer and restart it. Also note: this happens even if I quit using the torrent client before the freeze happens. So, for example, I'll use bitcomet, download something for a while, switch off bitcomet, and still, the computer gets stuck after a while (unless I restart before it happens).

At first, I thought maybe something was wrong with Bitcomet (latest version), but then I tried Tixati and Deluge, and they both had the same problem.

Another piece of info: I usually turn on Peer Block when I'm downloading stuff, but the problems happen regardless of whether I use Peer Block or not. I've also tried to use PB by itself without downloading any torrents, and none of the problems occured. So I definitely know PB isn't to blame.

As protection, I use Avira and Comodo, but I think this is completely irrelevant, because I've been using them for a long time, but the problems only started after changing my internet company.

As a result of those issues, I can't leave something to download while I'm out of the house, because the computer will be frozen for sure when I get back, usually before the download has had the time to make any real progress.

So basically that's it. Any ideas?

Thanks.

[kluelos]

Bittorrent clients will try to grab every bit of bandwidth that they can, if not restrained. Torrenting means that you are uploading at the same time you are downloading -- when you receive a piece of a torrent from someone else, you send that piece to other members of the swarm. This is an essential part of the process. Almost every transfer between peers requires mutual consent, and you must get in order to give. If other peers see you as an unreliable or slow source, they won't trade with you, so your download will slow to a halt very quickly. You must upload.

For every TCP packet that you receive, you must send back an acknowledgement. The sender waits for that ACK to tell them that you got the last packet and are ready for the next one. If they don't get the ACK from you, then after a while they will send the previous packet again, and start waiting again. This will keep up until they get an ack from you or eventually give up and abort the transmission.

Your internet connection is asymmetrical. It's faster down than up. When you are browsing the web, you are sending those ACK's back upstream for every packet that you receive. Bittorrent is sending ACK's too, in addition to what it is uploading. This all goes into your upstream connection, the slower side of things, so it can start to back up. Packets are waiting in the queue before being sent on, and this includes those ACK's.

If the queue gets too long, those ACK's start expiring (they all have a limted "time to live") before they get where they're going. They die before they get there. The web site you are browsing never gets its ACK, so it sends the last packet again. You already got that packet, so there's nothing new in it. Your browser sends another ACK, but there's nothing new to display. It looks like your browser has stalled.

This can also happen to the bittorrent client's own ACK's, so that it even interferes with itself.

Solve this by limiting your bittorrent client's global maximum upload bandwidth, to about eighty percent of your measured upstream bandwidth. That's usually low enough to prevent the problem.

You will also need to use BitComet in "No Listen Port" mode, because with your Pocket WiFi connection -- which is actually a wireless cellular or 3G connection similar to a mobile phone, you will never be able to unblock your listen port, to "become connectable". You are being blocked by an upstream firewall and won't be able to change that. It will greatly slow down your connection and interfere with your seeding. That will make it difficult to maintain a good ratio on most trackers.