View Full Version : Internet connection fails/drops when running uTorrent

Oct 3, 2012, 08:46 PM
Hi guys,

I'm running uTorrent 1.6.5 on a Macbook Air late 2012 with 8GB of RAM running OSX 10.8.2. While running uTorrent and downloading a few torrents I've noticed that my internet connection from that machine seems to drop out and fail to connect to websites and ping responses start to drop. I've limited the download and upload speed to roughly half my ADSL sync speed and the internet connection on other machines seems to be fine.

It's bringing back memories of running Windows XP and having to run the TCP patcher to increase the half open TCP connections setting. Is there some setting like that on a Mac that would limit the number of capable connections? I've found some information on the following page:


and I've changed the following settings:

Johns-MacBook:~ root# cat /etc/sysctl.conf
but there's still no real improvement.

By my reckoning, there's got to be something limiting the number of TCP connections on the mac where utorrent is running since the internet connection works fine on other machines connected via the same router.

Please don't post suggestions to limit the upload/download bandwidth since this isn't the problem a) because other computers on the same network work fine and b) because the bandwidth monitor on the router shows maximum bandwidth saturation at 40%. Is there some setting on mac's which limit the number of open tcp/udp sessions?

I've also tried transmission and I'm having the same issues with that too. If I run utorrent on a windows PC with the same sessions, I don't have these issues... This is really bugging me!

Has anyone got any ideas?



T'hain Esh Kelch
Oct 4, 2012, 03:00 AM
Does it also happen with other clients?

Oct 4, 2012, 03:44 AM
No, other windows clients do not have this problem...

T'hain Esh Kelch
Oct 4, 2012, 03:53 AM
Windows clients? I'm talking about torrent clients.

Oct 4, 2012, 04:21 AM
Oh sorry. Yes, happens with transmission as well...

Oct 4, 2012, 08:46 AM
Have you tried Utorrent at a friend's house, preferrably one with a different internet provider? The provider could be the issue. I no know locally the cable internet provider will throttle and totally mess with torrent downloads while the local DSL provider does not.

Oct 4, 2012, 09:10 AM
Oh sorry. Yes, happens with transmission as well...

Try lowering the number of concurrent connections allowed in uTorrent. Not the speed, but the number of connections.

Oct 4, 2012, 09:43 AM

Other windows clients on the same Internet connection don't have this issue and my ISP doesn't perform packet shaping/throttling. I have used the laptop with 2 other Internet connections anyway and the same problem exists. I have also played around with the number of connections to no avail.

This is really weird behaviour... Never seen it before other than windows xp prior to the half tcp open sockets hack.

Oct 4, 2012, 10:37 AM
I would suggest just going to BitTorrent, it's from the same people as uTorrent and basically runs the same...

Feb 9, 2013, 11:52 PM
Gyrex, long shot here, but did you ever find a solution? I'm facing the exact same issue.

Feb 10, 2013, 07:23 AM
I ended up running Deluge on my media PC for downloading torrents. Sorry, I know that's a rather useless response but I couldn't get much assistance in regard to this matter... I reckon there's some hidden connection throttling but I couldn't figure out where the settings were... Update the thread if you have any success though...

Feb 10, 2013, 07:46 AM
I run a pc on windows 8 and I'm pretty sure my cable provider is killing my connection when downloading torrents.

Feb 10, 2013, 08:07 AM
I run a pc on windows 8 and I'm pretty sure my cable provider is killing my connection when downloading torrents.

*sigh* I really appreciate you trying to help but I do wish people would bother to read posts in full before posting superfluos replies.

Per the OP, the internet connection works fine (I originally tested on other devices/laptops/phones/PC's etc). The network connection (not just internet but LAN traffic) dies on the Mac when running a torrent app.

Feb 14, 2013, 04:25 PM
I tried going to the utorrent 1.9 beta, going back to 1.5, back to 1.0, transmission, connection directly to the modem, changing VPN providers, all with the same result, complete Internet disconnect until I reboot my Mac. I never had this issue with snow leopard on my previous MacBook Pro. My mini is only 6 weeks old, so I'm going to open a support ticket with Apple and see if they can help me resolve this. I had thought it was a utorrent problem until it happened on transmission, it's got to be an apple setting somewhere.

On a side note, I did run utorrent for about 2 hours without my VPN (I downloaded about 6 different versions of the Pirate Bay AFK movie at the same time) and I was getting almost a constant 5.9MB the entire time and no connection freeze. So...?
But, for me, sometimes my connection lasts 30 min, sometimes 4-5 hours.

Feb 15, 2013, 05:31 PM
I'm probably jinxing it but, its been 8 hours so far, no freezing. Last night i dumped any software i dont need, including perian (I heard it was a trouble maker for Mtn Lion). I'm going to work now so i'll post when i get home wether or not it stayed going while i was gone.

Feb 16, 2013, 06:55 PM
Well, i wish i could nail down exactly what it was, but its been working fine for 30 straight without any drops. I have upgraded my computer from 10.3 all the way through 10.8, I've migrated through 4 or 5 macs since 10.3. I spent about 3 hours looking through all the library files, on every level, searching for things that were out of date, classic, ect. Dumped them. I found a program online (free) called Etrecheck that looks for old software that isnt loading properly in 10.8 and i deleted everything i could think of that i didnt need including perian. So far so good.