uTorrent slows down DL speed when limiting your Upload Speed. How to fix?

BrainY

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Nov 28, 2012
385
1
18,815
Anybody else noticed that your download speed goes down when you limit your upload speed? I used to not have this problem. I can't download anything without having to upload at full speed.
 
Solution
I complete guess, but uTorrent may be rate limiting ACK packets along with actual file transfer data. normally you can't do this because TCP ACK packets are handled by the OS, but many BitTorrent clients have a UDP based protocol called uTP and the "ACK" packets, quoted because they're logical ACKs not official ACKs, are handled by the program.

I don't use uTorrent anymore because of some major bugs and riddled with ads, but there was an option "Options -> Preferences -> Bandwidth -> untick 'Apply rate limit to transport overhead'" You could try unchecking this if it is checked. Otherwise you'd have to ask in their forums or wait to see if anyone where knows.

Kewlx25

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"I can't download anything without having to upload at full speed."

Did you mean you can't download at full speed while uploading?

If so, that's normal. In order to download, you need to (ACK)nowledge that you received the data, otherwise the sending side slows down and assumes you didn't. If your upload is maxed out and you can't upload ACK packets in a timely fashion, your download will slow.
 

BrainY

Distinguished
Nov 28, 2012
385
1
18,815
I used to upload at 10KB/sec and I would download at full capacity. Now with the new uTorrent program, I download only at 100KB/sec with that upload speed. If I just type in "0" for unlimited then it will download at full speed.

Basically if you don't upload at full potential, you wont receive a download at full potential it seems like.
 

Kewlx25

Distinguished
I complete guess, but uTorrent may be rate limiting ACK packets along with actual file transfer data. normally you can't do this because TCP ACK packets are handled by the OS, but many BitTorrent clients have a UDP based protocol called uTP and the "ACK" packets, quoted because they're logical ACKs not official ACKs, are handled by the program.

I don't use uTorrent anymore because of some major bugs and riddled with ads, but there was an option "Options -> Preferences -> Bandwidth -> untick 'Apply rate limit to transport overhead'" You could try unchecking this if it is checked. Otherwise you'd have to ask in their forums or wait to see if anyone where knows.
 
Solution