Internet connection fails/drops when running uTorrent

[gyrex]

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:

http://rolande.wordpress.com/2010/12/30/performance-tuning-the-network-stack-on-mac-osx-10-6/

and I've changed the following settings:

Johns-MacBook:~ root# cat /etc/sysctl.conf 
kern.ipc.somaxconn=4096
kern.ipc.maxsockets=8000
kern.ipc.nmbclusters=32768
net.inet.tcp.sockthreshold=16
net.inet.tcp.sendspace=262144
net.inet.tcp.recvspace=262144
net.inet.tcp.delayed_ack=0
net.inet.tcp.slowstart_flightsize=4
net.inet.tcp.blackhole=2
net.inet.udp.blackhole=1

but there's still no real improvement.

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

Has anyone got any ideas?

Thanks,

John

[vadimt]

Hi,

Could you please set download limit in uTorrent as 95% of your internet speed, check "Automatically manage bandwidth" in Preferences --> Bandwidth tab, start downloading anything and check your internet connection again?

Thanks!

[gyrex]

I actually set my upload & download bandwidth to 50% of my adsl sync speed... Setting it to 95% would saturate my connection...

As mentioned, no other computers attached to the router are affected, only the computer which is running utorrent so it doesn't appear that it's a bandwidth issue. I've tested using both wifi and ethernet.

[gyrex]

Has anyone got any ideas on why utorrent on osx/mac is playing havoc with my network connection? As stated before, internet access on other clients/computers connected to the same router aren't affected. Is there some setting on mac's which limit the number of open tcp/udp sessions? Upstream and downstream bandwidth usage (monitored from the router) shows about 30% overall usage.

[ciaobaby]

I actually set my upload & download bandwidth to 50% of my adsl sync speed... Setting it to 95% would saturate my connection...

Correct! Which is exactly why you were asked to do that and re-run the tests!

[vadimt]

Has anyone got any ideas on why utorrent on osx/mac is playing havoc with my network connection? As stated before, internet access on other clients/computers connected to the same router aren't affected. Is there some setting on mac's which limit the number of open tcp/udp sessions? Upstream and downstream bandwidth usage (monitored from the router) shows about 30% overall usage.

You could try to reduce a number of connections in uTorrent Preferences (uTorrent --> Preferences --> BitTorrent --> Connections). It should help.

Thanks!

[NipRing]

I'm having this exact same issue. Utorrent, after running for anywhere between 20 min and 3-4 hours (with 4-5 torrents downloading), will freeze up the internet connection to my new mac mini. My vpn shows 0 up and 0 down. My web browser no longer opens any pages nor will my vpn reconnect. My computer works fine but if i want to reconnect to the net, i have to restart my mac. But everything else on my network still works fine wifi included. I can't nail down exactly why it happens.I dont know how to tell what 95% of my internet speed would be either. I did just change the global connection limit to 200 and the per torrent to 40. I dont know if that will help. I know I pay $100/month for a 5MB/50MB connection and I hoped I wouldnt have to limit anything. OS is 10.8.2 with utorrent 1.8.2, router is netgear R6300 with most up to date firmware

.

[ciaobaby]

Sounds like a DNS caching problem, Try changing DNS servers to Google's public servers -> http://www.electrictoolbox.com/mac-osx-change-dns-servers-command-line/

[NipRing]

This is what it was at last night when it did it again. Note* I downloaded the 1.9 beta, and trashed my previous settings and was using the defaults.

I just changed the dns servers now and I'll report back with any results.

Thanks ciaobaby

[NipRing]

Well, it seemed to be running ok for about 2 hours but when i clicked on the drop down arrow for the download speed at the bottom of the utorrent window, i got a spinning beach ball and the connection immediately froze. Heres what was happening

I'm wondering if its (and im purely guessing here) the aftermarket ram i bought for my mac mini. Could this affect all this?

Edit* I had also just flushed the DNS cache.

Edit* Post restart -> I took this snap shot of what little snitch is showing me. And this is only with 2 torrents running at about 100 down 20 up. Seems like a heck of a lot of connections