Disabling 2.4GHz Radio on an iMac.

Question

Level 1

33 points

Disabling 2.4GHz Radio on an iMac.

Hi all, this may sound wrong but I would like to have the 2.4GHz radio on my iMac switched off so it only looks and connects to 5GHz networks. Is there a way to do this?

The reason is that for some reason when my iMac starts, it tends to find first my AX 2.4GHz network first and the performace feels very very different, much much worse performance. Before Mavericks this wasn't a problem, but when iCloud keychain was introduced it allowed all my devices to share the passwords and so, I currently have a problem, as I need my iPhone to connect to the 2.4GHz but my iMac to connect to the 5GHz radios respectively.

Thanks.

Jorge...

iMac, OS X Mountain Lion, 27in iMac . 2.8GHz i5 . 14GB RAM

Posted on Nov 23, 2013 6:28 AM

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Answer 1

Nov 24, 2013 9:45 PM in response to jorgefgr

I was serious about having you move up the 5GHz wifi.

System Preferences---> Network---> Advance---> Select your 5GHz network and move it to the top.

I've rebooted my Mac Mini several times, even changed out HDs to test another MBP. And each time that it turns on, it connects to my 5GHz and ignores the 2.4GHz.

See how I have the Elite-5G at the top of the list. Then the Pioneer after it, which is the 2.4GHz?

It was selected automatically at start up.

KOT

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Answer 2

Nov 24, 2013 11:23 PM in response to jorgefgr

I know this isn't exactly what you are looking for. But maybe it could help your iMac use the 2.4GHz band better.

Download the iStumbler app from http://www.istumbler.net

Scan the area to see if there are any "openings" for channels that you can use.

Then open your WiFi's base station settings page and force it to stay on one channel.

If you are using an Apple AirPort. Just open AirPort Utility and go to the Wireless tab. Click on Wireless Opitions...

And select the most opened 2.4GHz channel. Which happens to be 1 for me.

You could also change the Radio Mode to what I have...

802.11n only (5GHz) - 802.11b/g/n (2.4GHz)

I also have my Mac Mini on a Static IP. So no matter how many times it's been rebooted or the router been rebooted. It'll still have the same IP address.

I am going to mention this part, but I honestly don't think it would matter. I also have the IP Addresses 001 to 020 blocked from auto DHCP. Meaning, only Static IP Addressed devices, such as my Mac Mini, can only use those addresses. Which I do have my Mac Mini set up for 10.0.1.3

Again, using AU go to the Network tab and click on Network Options... at the bottom and just copy what I have...

I hope some of this helps. It could also be a combination of everything the way that I have it. I really don't know.

KOT

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Answer 3

Nov 23, 2013 6:55 AM in response to jorgefgr

Are the SSIDs the same for both bandwidths? If they are add a "-5G" at the end of the 5GHz. Then connect to it. Whenever you reboot or what not, your iMac should see that.

You could always delete the 2.4GHz in the Network pane. It'll only delete it off of the iMac.

KOT

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Answer 4

Nov 23, 2013 9:07 AM in response to jorgefgr

I just tested this with a reboot of my Mac Mini...

You can rearrange the order of what network you want to connect to first. I put my 5GHz on top of my 2.4GHz. When it booted up, it connected to my 5GHz.

System Preferences---> Network---> Advance---> Select your 5GHz network and move it to the top.

KOT

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Answer 5

jorgefgr Author

Level 1

33 points

Nov 24, 2013 6:50 AM in response to Kingoftypos

Nope, it does work but not all the time. I'm not sure about other computers, but my iMac tends to find first 2.4GHz networks and so, since it's in the 'Preferred Network' list, it connects to them first. I guess I do need a software switch to really 'disable' the 2.4GHz radio. I've even checked 'Require administration authorization to: - change networks' to no avail.

Can anybody tell me how can I accomplish that? Thanks..!

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Answer 6

jorgefgr Author

Level 1

33 points

Nov 24, 2013 9:33 PM in response to Barney-15E

In the newest operating system 10.9 Mavericks, the networks are kept synced and so, if you have the 2.4GHz network added to the iPhone, your iMac will also know its password and will connect to it when available. And it will connect to it especially if it is seen before it detects the 5GHz network. If you try to remove the 2.4GHz SSID from the iMac's 'Preferred Networks' list to prevent the iMac from joining it, you'll be warned that it will also be removed off the iPhone, which isnt' what I want/need.

And so I go back to my original question: Is there a way to disable the 2.4GHz wireless radio off an/my iMac? This, I reckon, would solve my problems.

Please advise.

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Answer 7

jorgefgr Author

Level 1

33 points

Nov 24, 2013 10:23 PM in response to Kingoftypos

Hi Kingoftypos, I know what you mean, and I can confirm that the 5GHz is top on the 'Preferred Networks' list for as long as I can remember, this makes no difference as more often than not since Mavericks, my iMac connects to the 2.4GHz SSID. As to what reasons are there for your Macs to be able to always connect to the 5GHz first, I guess there could be a long list of whys, I dare not go there.

My question is still the same: If anybody knows a software switch for the 2.4GHz radio on iMac to be turned off, I would be much grateful if you shared with me.

Regards.

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Answer 8

Barney-15E

Level 10

122,426 points

Nov 25, 2013 5:31 AM in response to jorgefgr

I filed an ER on it.

And so I go back to my original question: Is there a way to disable the 2.4GHz wireless radio off an/my iMac? This, I reckon, would solve my problems.

Please advise.

If there was, we wouldn't be trying to work around the issue.

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Answer 9

Barney-15E

Level 10

122,426 points

Nov 25, 2013 5:49 AM in response to Barney-15E

Here is something to try. I did this and my 2.4GHz network has not reappeared in my list like it did when I tried in the GUI. It might back-door the removal and iCloud Keychain doesn't get notified.

In Terminal, run this command, replacing SSID Name with your 2.4GHz network name:

networksetup -removepreferredwirelessnetwork en1 "SSID Name"

It is quite possible that your WiFi is on en0 or en2. You can list the networks with

networksetup -listpreferredwirelessnetworks en1

If you get an error that en1 is not a Wi-Fi interface, try en0, etc. until you get the correct one.

I have not returned to the GUI, but I have turned WiFi off then back on.

I don't know if it will work for you as my Mini's WiFi always selects the 5GHz network.

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Answer 10

Dec 7, 2013 4:54 AM in response to Kingoftypos

Unfortunately, moving 5GHz up in the preferred network list doesn't solve the problem.

My mid 2010 iMac (MC510) doesn't see the 5GHz network (channel 36, 40MHz wide) when the computer wake up after sleep. The 5Ghz network is not listed in the network list at all and appears in the list after multiple wi-fi off-on switching.

I hope that switching 2.4GHz band off can solve the problem, but obviuosly that chances are low. MC969 MB Air works just fine in the same location. Seems that this is hardware or driver bug (limitation) either.

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Answer 11

jorgefgr Author

Level 1

33 points

Dec 7, 2013 5:56 AM in response to jorgefgr

Yes, that is precisely the problem with me as well. And although I do have internet at all times, the performance of movie streaming (from the iMac to the AppleTV) especially is very very different when the iMac isn't on the 5GHz network. So as a precaution I have to confirm upon startup that the network the iMac is connected is the 5GHz one or manually switch.

:-S

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Answer 12

jorgefgr Author

Level 1

33 points

Nov 23, 2013 7:02 AM in response to Kingoftypos

The networks IDs are different. In order for the network not to be re-added on the iMac, I also need to delete it on the iPhone, which I don't want.

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Answer 13

Barney-15E

Level 10

122,426 points

Nov 24, 2013 7:14 AM in response to jorgefgr

There shouldn't be any interaction between devices as to the networks they see. You should not need the 2.4GHz network in your list of Preferred Networks on the iMac.

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Answer 14

Barney-15E

Level 10

122,426 points

Nov 26, 2013 4:16 AM in response to Barney-15E

Sorry, as of this morning, the other network is back.

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