iMac ethernet is slow, internet and wireless fine.

Question

iMac ethernet is slow, internet and wireless fine.

Hi,

In our office we are having trouble with the ethernet speed on one computer. If another computer is pluged into the same network port the speed is fine. This eliminates any cable issues.

When transfering a 600mb the speed is super slow (around 450kb/s). On the same iMac when using wireless the speed jumps to about 4.5mb/s.

I have tested the internet speed on both connections and they are about the same.

When transfering a file to the iMac from another computers public folder on the network the speed is great, we achieved about 45mb/s!

This leads me to think that our server (Xserve intel running 10.5) is slowing down the file transfer speed from our xserve raid on the ethernet connection only for some reason.

It would be great to get some advice on this issue.

Thanks

iMac, Mac OS X (10.6.8), Conected to Xserve on 10.5

Posted on Aug 21, 2012 6:58 PM

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Answer 1

BDAqua

Level 10

239,435 points

Aug 23, 2012 1:23 PM in response to Patrick @ SPA

Whew!???

Open Network Utility in Applications>Utilities>Info tab, select Ethernet & what is the Link Speed & are there any Errors/Collisions on the right?

Open Console in Utilities & see if there are any clues or repeating messages when this happens.

10.5.x/10.6.x/10.7.x instructions...

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

Normally Local connections should be below the top.

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Answer 2

Aug 23, 2012 8:15 PM in response to BDAqua

After I made this post I found another fourum that suggested changin the speed to 100basetx in the ethernet settings. I did this and the speed is comparible to a 100baseTX connection on other computers in the office.

So when I change it to 1000tbase its very slow... 100baseTX is fine.

I did check console and a repeating messge is:

(edu.mit.kerebos.krb5kdc [14729]) Existed with exit code:1

then a throttling respawn message then a cant get profile to fetch relmes message.

Would this have anything to do with it?

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Answer 3

BDAqua

Level 10

239,435 points

Aug 23, 2012 9:26 PM in response to Patrick @ SPA

Generally when a slower Speed works it's either the Ethernet Card being Flaky, or a bad Ethernet cable, or less than a Cat5e or Cat6 cable.

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Answer 4

Feb 19, 2015 8:42 AM in response to Patrick @ SPA

Hi

I just got an iMac 27" with 5k retina. I got the same issue with wired network at home. My network line is 150/20mbit, and with wifi only, i get speeds close to this (speedtest.net). With cable only, i get around 20mbit down and 5-6 up... If i set the network hardware down from 1000basseT to 100baseTX, i get around 93mbit down and 10 up.

Other pc´s with windows on the same gigabit hub has no issues. Tried different cables...

Any ideas?

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Answer 5

Feb 23, 2015 11:31 AM in response to BoBfromheer

i got the same problem in may brand new iMac5k retina, My net work line is 300/100Mb, got speeds of 180-190Mbs while using wifi connection, but dropped to only 94-95Mbs while using the ethernet cable connection.

Why ?

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Answer 6

Feb 24, 2015 11:12 PM in response to BoBfromheer

After some testing yesterday, I made a new user to test with. And guess what... speed went up with local wired transfers again.

I was using only one admin user on my new iMac. (not so familiar to macs yet 😉)

Will test some more today, with different wired/wifi settings.

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Answer 7

Feb 25, 2015 8:35 AM in response to BoBfromheer

Think it was too late in the evening...

I had turned off my windows pc, just when I created the new account. Thats why the speed went up.

When I tested again today, I got slow wired network again.. with the windows pc on. Turned it off, and speed went up.

What is going on here... can't we have two different systems on the same network? That´s bs...

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Answer 8

Feb 26, 2015 11:15 AM in response to BoBfromheer

Update... did some testing with iperf today. I get slow speeds in to my iMac, but out is max... 12-19Mb in and 800-900Mb out. How come?

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