User profile for user: CmonThisMustNotBeTaken
CmonThisMustNotBeTaken Author
User level: Level 1
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Dual monitors kills dead the Wireless network.

I can hardly believe this myself... but - when I plug in a second monitor the wifi connection goes dead.
Unplug it, network back. Leave it plugged in, power off the monitor, it is ok, power back on, network dead.

Has anyone else seen this problem - it is absolutely reproducible and without a doubt caused by the second display.

Needless to say this is unusable.

Monitors 2x Dell 2007FP, using DVI.

Model Name: Mac mini
Model Identifier: Macmini3,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.26 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 2 GB
Bus Speed: 1.07 GHz
Boot ROM Version: MM31.00AD.B00
SMC Version (system): 1.35f1

2009 mac mini, Mac OS X (10.6.4), Mac Mini

Posted on Sep 16, 2010 3:17 PM

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12 replies
User profile for user: captfred
captfred
User level: Level 7
26,446 points

Sep 16, 2010 5:14 PM in response to CmonThisMustNotBeTaken

In this article:

http://support.apple.com/kb/HT1365

It refers to:
Certain external monitors and LCD displays: Certain displays may emit harmonic interference, especially in the 2.4GHz bandwidth between channels 11 and 14. This interference may be at its worst if you have a portable computer with the lid closed and an external monitor connected to it. Try changing your access point to use 5 Ghz or a lower 2.4 GHz channel.

So give a different frequency a try and see if that helps.

Cheers
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User profile for user: CmonThisMustNotBeTaken
CmonThisMustNotBeTaken Author
User level: Level 1
0 points

Sep 17, 2010 9:08 AM in response to captfred

Yup, it was that simple. I was somewhat surprised though.

a) That these monitors are able to completely mess the signal (yikes, think fried chicken!)
b) That the mac still thought it had a perfectly good wireless connection, even though it was getting massive packet loss.

BTW, of interest I tested 3 other dell laptops (Intel Pro Wireless) sitting in the exact same location (and with the screens on) and they were all 100% happy. So, probably much more like some internal interference within the mini itself - i.e. track interference on the board. Of note - it was only the mini display that did it, not the DVI port, again, pointing to internal interference on the mini board.
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User profile for user: CmonThisMustNotBeTaken
CmonThisMustNotBeTaken Author
User level: Level 1
0 points

Sep 27, 2010 4:39 PM in response to captfred

I have no idea, for couple of days now I've been fiddling with the channels, B,G,N and the rates.
For a while I think I've found a combination that works... then it goes again.

Drop the mini-port display down one notch in resolution and it is fine.
Like I say three laptops are connected just fine, 1 inch away from the mac mini setup... so this can't be "external interference".

This really is driving me nuts... do people think I've got a bad piece of hardware then?
I don't see this problem anywhere else on the internet for the mini...?
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Dual monitors kills dead the Wireless network.

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