05-21-2011, 12:46 AM

Hi all,
Did anyone already faced the same issue:

I'm downloading a torrent at 900kb/s just using my regular notebook display (Macbook Pro 13 early 2011). When I plug the thunderbolt-DVI to use an external display, my network becomes very unstable and slow. My download goes to 100kb/s in seconds. Took a lot of effort to notice this. I was thinking that was a router/ISP issue.
Thanks.

05-21-2011, 03:57 AM

Sometimes torrent downloads will vary quite a bit in speed depending on how many threads are being downloaded and uploaded at once.

Did you test to see whether the external monitor was causing the slow downs by removing it and then plugging it back in again?

05-21-2011, 10:58 AM

Yes. I did! The utorrent is showing, i.e: 900kb/s without the DVI cable plugged in. When I plug, in 2 or 3 seconds my downloads goes to 90-100kb/s... and there is a slow down in all aspects.. web browsing takes a long time to respond upon typing the url... etc etc...

05-21-2011, 01:07 PM

Science it up a bit….
Try running something like speedtest.net with and without the cable plugged in - does that cause a noticeable effect?

05-21-2011, 01:15 PM

Yes, The same happens. And the overall internet performance becomes pretty affected. I rebooted my router and cable modem many times during this week until I noticed this.. Any ideas how can I fix this?
Thanks

05-21-2011, 02:01 PM

Have you checked to see if you have installed the recent EFI update that was supposed to address thunderbolt issues? Make sure you run the installer in utilities if that was added...

05-21-2011, 09:22 PM

Yes. I installed! 2 weeks ago I think.

05-21-2011, 10:51 PM

I have the same Mac as you, with a 27" Cinema display plugged into the Thunderbolt port and have seen no effect on Internet speed as measured with this tool...
Speakeasy - Speed Test

Try it and see if you get the same result.

Using Verizon 4G through a tethered phone on a slow Win computer elsewhere on the home network, I get between 5mbps to 15mbps depending on the phone's signal strength. Again - zero effect with external display plugged in or not.

05-22-2011, 01:34 PM

I was able to figure out what is causing this lag. I switched to the HDMI adaptor and plugged the Macbook to my Plasma.. no issues at all.. I guess it's the DVI adaptor who is causing this issue. I will buy a new one this week.

11-06-2012, 12:05 PM

I had the same problem! When I connected my two screens with Thunderbolt -> DVI adapter my WiFi connection dropped. I had two no-name adapters bought at a mac reseller (the apple original was sold out). Went back to the store a couple of days later and got the Apple ones. Now my problems are gone!


BEFORE
http://i47.tinypic.com/161ztip.png


AFTER
http://i49.tinypic.com/2hnx944.png