My wifi drops when I plug in an external monitor through the thunderbolt port

Count me in for this one too...took me WAYYYY to long to make the conenction ( I have a new office and only use the big monitor at work). I've been complaining about the wifi at work for weeks. Today my mouse died, so I had to open it and and BOOM, blazing speed. ***. Channel Change didn't work....I'm bummed.

Has anyone managed to solve this issue? Thanks

Anyone else solve this? I need my MBP to be connected to my Wacom and this is killing me.

The only solve I have found is to leave the MBP lid open and use the monitor as the main display. I changed the channel of the router with no luck.

Unfortunately even with the lid open I still have no WiFi.

I am using a MBP-Retina.

So frustrating.

Mines a official adapter 😟

Hey. I actually found a solution to this. It's extremely weird and I called apple to talk to them about it but they had no idea what was going on. This isn't going to make any sense, but just try it. Lower your external monitors resolution.

I kid you not. I was having this same problem with my macbook pro "13 I bought two weeks ago. Plugged it into my external monitor and internet crapped out. Then I realized uplugging my monitor fixed the issue instantly. After doing some searching I found that lowering the resolution fixed it for one guy. My original resolution was 1400x1050, internet didn't work. I tried 1344x1008, internet didin't work. Went one lower to 1280x1024, boom, internet back to normal. I can switch between the resolutions and see it not working and then instantly working again at 1280x1024.

Hope this helps someone else.

Edit: I also found that if I change my wireless routers channel from 11 to 1, I could function at higher resolutions. Something else to try. I have no idea why that would be happening though.

I had the exact same problem. MacBook Air 13" mid 2012.

Solved it (at least it works now) by changing the wireless channel to 7 (instead of "Auto").

BTW: I don't have an original MiniDP adapter

I fixed this problem by switching the channel on my router from Auto to 1.

My setup:

2012 Macbook Pro 15" non-retina

Dell 2405fpw external monitor

Asus NT-R56U Router

Third-party DVI-Thunderbolt adapter

I'm having the same issue with wifi dropping when a display is plugged in. My setup:

- 2012 MacBook Air (OSX 10.8.2)

- Apple Cinema Display

- Apple brand Thunderbolt-DVI connector

- Airport Extreme Base Station

Wifi works fine when the same Thunderbolt cable is plugged into our iMac.

Plug Thunderbolt into the MacBook air and it kills the wifi. Unplug Thunderbolt and wifi comes back.

Ok this issue has been driving me insane!

My setup is as follows:

2012 15" rMBP

OSX 10.8.2

External Dell U2410 display (1920 x 1200)

MDP-DVI adapater from Monoprice

DVI to DVI cable connecting to display (3ft long if that matters)

Full size Apple keyboard (wired) connected via USB hub in display

External Apple Magic Trackpad (connected via BT).

I am 99.9% convinced this has nothing to do with the el cheapo Monoprice adapter and here is why:

MBP sleeping with lid closed. Wake by using keyboard. Wifi connects with full signal (according to icon on menu bar - this never changes). speedtest.net shows speeds at 1 - 1.5 Mbps.

Unplug adapter and plug back in immediately so the MBP doesn't sleep.

speedtest.net shows speeds of 15-16Mbps. This is the speed I should be getting and the same speed that I get when not using my external display.

Speed maintains until the next time my MBP goes to sleep. This can be for hours at a time the speed is maintained!

Wake and the same thing happens again. Speeds back to 1 - 1.5Mbps. {aside: It is almost like the speed is being throttled because it is always darn near exactly the same speed when performing poorly.}

Unplug MDP and replug... excellent speeds again.

Note that I can NOT perform this workaround when using the MDP next to the power adapter. This ONLY works with the MDP next to the USB.

The fact that I can get consistent speed after unplugging / plugging back in tells me this has absolutely nothing to do with interference as what many people have discussed. How could it possibly be related to interference when it works fine after unplugging / plugging back in for hours at a time?

This issue has been around for a long time (ie as far back at 2010) and really needs to be addressed by Apple.

this is ridiculous, if I use any other screen resolution than the default the internet works, if I return to default the wifi craps out... how is this happening in 2013 after so many macbook iterations ? my MBA is 8 months old, there were three osx updates... this *****

I agree. I have a late 2011 11" MacBook Air that I am trying to connect to a 23" Cinema HD display. As soon as I do, it kills my wireless. It still shows that I have full bars but I have no speed at all. As soon as I unhook the monitor, wireless opperates as it should.

I am using this in a work environment so making a change to the router channel is not as simple as if I was at home.

Any other help anyone can lend would be great.

I am relatively certain that the WiFi channel has absolutely nothing to do with it.

choots79 you are the first person to mention issues with a Cinema display. I am very surprised to hear that an Apple display doesn't work with the MBP. Unfortunately this lends more evidence to the fact that there are issues with the Thunderbolt port. I have to believe that it is a software issue so here is hoping that Apple actually fixes it.

I thought it was an issue with the mini Display port to DVI adapter I was using so I bought a new one from Apple today and it still does exactly the same thing.

Very disappointed.