Jump to content

I'm experiencing an invisible upload speed cap


Recommended Posts


I've been using utorrent for a long time, usually without any problems. But lately I've been experiencing some weird behaviour.

I usually set both a max down and upload speed to ensure that I maintain a proper ratio between down and upload.

This normally works fine and the actual speeds end up at the maximum values I've set.

But lately my upload has started acting weird. The speed caps at a lower value than the one I've set. If I set it to unlimited, it quickly goes up to my connection maximum. If I set a limit, the speed drops way below that.

Lets take an example:

I set my upload cap to 150 kb/sec.

After a while the total upload speed of the 5 torrents I am seeding is steady at 90-100 kb/sec.

I change the upload cap to unlimited.

After a short while the upload speed rises to and stays at 190 kb/sec.

I set the cap to 150 kb/sec again.

The upload speed drops to 90-100kb/sec and stays there.

Why is this happening? Any ideas?


Link to comment
Share on other sites

I've seen that myself and think it's either due to hostile ISPs, high levels of random packet loss, overload conditions with networking hardware/software, and/or pipelining issues with very few connected peers to upload to.

Starting with...what settings are you using in uTorrent -- as shown by Speed Guide CTRL+G and any advanced settings you've changed?

What's the "quality" of the torrents you're running?

Do they have lots of peers and seeds?

Are the peers generally very fast broadband connections...or closer to dial-up?

Are you using a Belkin router, USB network card, or wireless connection?

(These tend to be problematic with lots of connections at once.)

Lastly, what software firewall and antivirus are you running?

These too can really screw with uTorrent. :(

Link to comment
Share on other sites

I'm using whatever standard settings utorrent installed with (I set the speed to xxx/2 mbit).

The quality, number of peers and speed of them is very high/very good (as in there are lots of peers and I know they can download more than I can upload).

Standard wired adsl with no software firewall (Avira antivirus with nothing but antivirus enabled).

The weird thing isn't the lower speed, speeds are always very good here (I can max out my connection easily with the same torrents), the weird thing is that whenever I set an upload speed cap, the upload speed drops way beyond the cap (like in the example).

I'm trying to get utorrent to actually use the speed limits. I.e. I can upload at 190-200 kb/sec if I set the upload limit to unlimited, but only 90-100 kb/sec if the upload limit is 150 kb/sec.

Why isn't it at 150 kb/sec with the limit on, when it 1 minute earlier uploaded at 190 kb/sec without a limit?

This happens regardless of whether I download or not at the time (download is usually at 100 kb/sec) (my connection is 8mbit / 2mbit).

Link to comment
Share on other sites

If you're connected to very few peers (fewer than 5) then it could be bad networking on the part of the peers you're uploading to...

If the problem's on your end, then Windows tweaking with TCP Optimizer may help slightly...just be very careful not to allow lots of server connections in it at once!

Link to comment
Share on other sites

The torrents I'm uploading at the moment have 50+ leeching peers each. I'm connected to about 20-30 on each.

I know they (the peers I'm connected to at the moment) can handle at least the 200 kb/sec upload that I can send out (as in, I can send to them at 200kb/sec if I just set the limit to unlimited).

The problem may be at my end, but I honestly cannot figure out how this can possibly be a problem related to anything but utorrent. :/

With a single seeding torrent at 20 something connected peers, I can upload at around 190-200 kb/sec with no upload limit set in utorrent.

With the same torrent and the same peers in the same utorrent session, if I set an upload limit in utorrent of 150 kb/sec (40-50 kb/sec less than the speed at which I'm currently uploading), the actual upload speed will drop to 90-100 kb/sec and stay there.

Edit: I just tried something else. I set it to unlimited and it uploads at 190 kb/sec. I then set the limit to 200 kb/sec and the speed drops to 100 kb/sec.

Link to comment
Share on other sites

What are your upload slots set to?

How many peers are you actually uploading to at any given moment?

Do you see any peers that switch from a "U" flag to "u" flag after you set upload speed to something other than unlimited?

Are there any messages in uTorrent's LOGGER window to give hints what's going on?

(You may need to turn on verbose mode and/or monitor ALL kinds of traffic...it will be very hard to sift through!)

Did you try Windows network settings tweaking with TCP Optimizer?

(You will need to read quite a lot to understand what it does!)

Are you using uTorrent v1.9 alpha?

Link to comment
Share on other sites

Thanks for you time :)

I'll look at these items after work.

Sorry for the delay, I have been busy for a while :)

Upload slots are set to 25 (with the option to increase when speed is <90% enabled).

Global maximum number of connections is 700. Maximum per torrent is 60.

Atm I'm uploading to about 70 peers, the number changes, but the invisible cap behaviour is there regardless of the number of peers.

The peer flags don't appear to change, nor does the number of connected peers, when I change the upload speed to unlimited.

As far as I can tell (I'm not a log expert though :) ) there is nothing in the log that indicates what is wrong.

No, I haven't used the TCP optimizer because I generally don't trust those "optimizer" applications as something machine-specific like optimization cannot and should not be generalized. (I haven't tried this particular optimizer, it might work)

I'm using utorrent 1.8.2

Link to comment
Share on other sites

  • 4 weeks later...

Go read how TCP Optimizer works before running it...preferably TWICE.

It's not a typical speedup program, but some of what it does may be what others do to make themselves "look good".

Try lowering the number of upload slots so that there's about 10-20 KB/sec upload speed PER upload slot. More is not always better or faster. uTorrent will still use more (after 30 seconds to 2 minute delay) if it really needs to.

Does there seem to be an invisible upload speed cap PER peer you're uploading to?

(as well as the global one)

Try sorting by upload speed to see if you're uploading to most of the peers at <1 KB/sec.

Link to comment
Share on other sites

I'm having the same (or close enough) issue as the OP.

Everything IS set correctly, uTorrent is running default, I've just installed it (got tired of UDP errors in vista and the previous torrent client I was using).

I have a 7mbit adsl connection, that hits the upload cap at 400kb/s.

Everything runs fine, I was able to upload steadily at 40kB/s (10 I reserve for my own downloading and surfing, sounds fair to me) with other torrent clients. (and I still am if I load another client)

Now.. the upload speed on uTorrent is always low, bouncing around 25-20kB/s.

The only difference is that it still shows that weird "limit" even if I set the upload as unlimited. it shoots up to 50 in a couple seconds, but then drops back to 20 again.

Doesn't matter if I have one or three torrents running, if I'm only seeding, or only downloading, or both.

Have tested it a bit more, with exasperated settings (like 3000 or 10 connections, different upload slots, half-open connections) to see which one could be the culprit by pushing it to the limit.. but it doesn't change the result at all.

Sadly, I believe that's a showstopper for me. everything else about uTorrent is great, but from my own point of view, it kinda fails the idea of using torrents, if I can't upload good enough to the other people. I feel like I'm leeching.

Not saying it's uTorrent fault, more likely than not it's something wrong on my own side that I can't figure out..

I just don't see why, short of any setting I could change on the client, other BT clients work and this one doesn't.

Going to head back to my trusty (but always complaining about UDP) dinosaur-powered client, if I won't be able to overcome this nuisance.

[edit, to add: No, my ISP is not throttling me.]

Have a good time, and thanks for the efforts put on this neat piece of software.



Intel Core2Quad Q6600

4gb ram ddr2 800

Vista 64bit


Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...