Internet speeds Mac vs. Windows

[fronheiser]

I have an interesting problem I haven't been able to figure out.

Recently my home was upgraded to 100Mbps/5Mbps internet. In my home office, I have 3 systems that are wired, either to an gigabit ethernet switch or directly to the cable modem/gateway (a Netgear CG3000D).

My 2 Windows laptops are getting the 100Mbps downloads as advertised on the tin. My 6 month old iMac, running 10.7.2, seems to have about 1/2 the download speed (about 50Mbps). Very, very odd.

Does anyone have any ideas as to why this would happen?

 

[hakuryuu]

That is quite odd and nothing comes to mind as obvious, especially since I can't poke around your iMac or router/modem.

One thing to check is what your MTU is set to. You can see this in (terminal > "ifconfig | grep mtu" and look for en0 (ethernet) or en1 (airport)) or (system preferences > network > whatever interface is at the top of the list > advanced > Ethernet) . It is probably 1500 which is pretty standard and is unlikely to really effect performance unless your isp specifically states that 1492 or something is better, but again shouldn't matter much.

Also.. is everything on ethernet? Wifi could be the culprit as it really tends to not get the advertised bandwidth.

 

[fronheiser]

That is quite odd and nothing comes to mind as obvious, especially since I can't poke around your iMac or router/modem.

One thing to check is what your MTU is set to. You can see this in (terminal > "ifconfig | grep mtu" and look for en0 (ethernet) or en1 (airport)) or (system preferences > network > whatever interface is at the top of the list > advanced > Ethernet) . It is probably 1500 which is pretty standard and is unlikely to really effect performance unless your isp specifically states that 1492 or something is better, but again shouldn't matter much.

Also.. is everything on ethernet? Wifi could be the culprit as it really tends to not get the advertised bandwidth.

Everything is on ethernet. The Windows machine is even connected to a gigabit ethernet switch and is still twice as fast as the Mac. I thought it was a duplexing issue, but ifconfig is reporting full duplexing and everything seems as it should be.

I know that 50Mbos is nothing to sneeze at, but I'm completely lost as to why the Lenovo sitting right here next to it is seeing double the results running the same speedtest to the same server.

 

[derbothaus]

Certain modems that are provided by cable companies just don't work well with OS X. RCA modems had issues while Motorola was fine. I ended up buying my own after 2 returns. Speed is great now. Just recently had a client who had the same issue but with only a 16Mb line. Mac got 2-5Mb. Swapped out the modem and the Mac immediately hit 16Mb. Just a thought. Try another Mac if you can get ahold of one. Then maybe a different DOCSIS 3.0 modem.

 

[mmomega]

No clue, as I have the same internet service as you and I am also on an iMac on ethernet.
Maybe try in a different browser or update to the latest flash, since most speed tests use flash player to display the info. May or may not do anything.