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uTorrent using many ports and freezes web traffic...!


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Question #1:

Most of the time my verion of uTorrent (newest verion 1.6, dowlnoaded from this site) just stops all web traffic (I can't browse the web) when it is running. This wasen't the case with older versions.

This happens directly after opening uTorrent, even if there is a total of 0Kb/s download or upload in uTorrent and even if ALL torrens are stoped.

I have gone throug this list of "slowed/interrupted Internet connection":


But nothing has helped yet.

Any ideas?

Question #2:

In my firewall ...(newly installed, the problem above started before I innstalled this firewall and I have configured it to allow uTorrent)... I can monitor the whole network in my computer... and when uTorrent is running it is using ALOT of ports:


Even so that I have configured uTorrent to the port 4444

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Yes, I have disabled DHT and UPnP and restared the computer many times and the router some 2-3 times.

Once I quit uTorrent, I can see on the network list in my firewall, that while uTorrent is using ALL those ports my web browsing just won't start.

After quitting uTorrent it takes like 10seconds for all the ports being used to be cleared off that list and straight away, the web browser pops up with the page that was continuosly loading (while the ports where still open in that list).

So.... I open uTorrent -> web traffic stops. (sometimes it acts like 56K)

Once I quite uTorrent -> takes 10sec. for the ports to close and after that, web goes to being fast as normal.

I'll be happy to post any information you wan't....logs og anything.

P.s.: I read your link, Ultima, about those random ports between 1-5.000...

But that dosen't answer why my browsing traffic freezes...

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Yes, (forgot to mention that) I already am connected straight to the modem via ethernet.

I just noticed something... when uTorrent is running my browsing instantly dies. And if I close FireFox or IE then I can't open those browsers again. I first have to close uTorrent, wait 10sec for the ports it uses to close and first then I can re-open FireFox/IE.... strange.

While uTorrent is running, if I try to open FF/IE it just hangs (the FireFox.exe is running in Task Mannager but it doesn't open/start.)


I installed Azureus and web browsing works fine with it...

But it takes more memory....hehe

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Hi, iv'e been real busy lately sosorry for the late reply.

Nothing has fixed my problem yet. I did donload the latest uTorrent 1.6.1 (old version was 1.6.0) and everything worked fine for 2 days. That is, I was able to run FireFox with uTorrent. But then after 2 days or so they stopped working together.

My firewall is set to Low (let's all apps connect to inthernet that need to) so that can't be it.

For the time being i'm just using Azureus.

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Skullaxe, most of that is completely normal behaviour.

When one application initiates communication with another by TCP, it must specify a destination port number (because TCP requires destination and reply port numbers). For most web servers, that's port 80, as an example. That's for initiating. Your listen port is the one your client is listening on for other swarm members to initiate contact with you -- just as you use their listen ports to initiate contact with them. A connection that somebody else starts is an "Incoming" connection and gets flagged as "I".

The TCP packet contains a second port number, which is the reply port. The web server or other application sends its reply using that destination port, which your computer recieves because it's expecting an answer on that port. The reply port is chosen fairly randomly and is done per connection.

So any applicaton using TCP to communicate with another app is going to have replies incoming on many different ports. That's how it works and is entirely expected. Your firewall monitors the outgoing packets, so it knows to expect a reply from that destination, using that reply port. This is the first part of what you're seeing.

When you join a torrent swarm, you send your IP address and your listen port to the tracker, which adds you to the swarm, and sends this info to all the other members when they scrape. When you leave the swarm (assuming you do this correctly and not just terminate the client), a termination message tells the tracker to remove your info from the swarm list. Other clients aren't going to get that info until they re-scrape, so it can take quite a while for everybody in the swarm to get the word that you're no longer part of it. In the meantime they'll continue to try to connect to you, or to use an existing connection to negotiate with you. That'll continue until they either drop you or get the word that you're not in the swarm anymore. Until then, you'll keep getting traffic from them, gradually dropping off as they individually re-scrape and get the revised list. This is nothing unusual or anything to worry about.

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  • 4 years later...

yeah this is happening to me too. this is so annoying utorrent hasnt done this before, and for the past 2 months has been doing the same thing to me. ive been reading the threads made by other users having the same problem, and trying some things. just dont understand why this would be 'normal' behavior. utorrent did not used to do this. my speed is 100Mbps down, 5 Mbpps up, its nothing to do with speed.

didnt mean to bump a super old thread if anyone has a problem with it. sorry in advance!

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Why such an odd speed combination?

20 times as much download as upload...insane!

Incoming connections should only go to uTorrent's listening port, but they can be on any port of their own.

Outgoing connections should be using ephemeral ports...and can be QUITE numerous over the course of 10+ minutes.

Is DHT enabled? ...Or other features that create connections on their own?

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