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

Another solution which works in my case (MBP15 2016, external monitor via non-original hdmi-typeC adapter) is to wrap cable with Kanthal A1 wire (ferritic iron-chromium-aluminium alloy).

Not sure why, but foil did not work in my case.

This was the only thing that worked for me also! Tin foil to the reduce. I have a brand new 15" 2016 MacBook Pro. Apple really needs to find a way to stop this from happening, having tin foil next to my nice new computer is not ideal.

Mine was also fixed by changing to channel 1 (D-Link router was set to auto-select and was using channel 5). I'm NOT using thunderbolt.

My old configuration:

• MacBook 3,1 (that's right 2007!)
• Mini-DVI to DVI to Dell2001FP (lid not closed--spanned, not mirrored)

Wifi immediately stops working with external monitor connected with native 1600x1200 60Hz. Lowered to 1344x1008 60Hz, still does not work. Lowered to 1280x1024 75Hz and it works. Changed router to channel 1 and native resolution works! I'll repost if anything changes.

I now recall having this problem over a year ago but since others on the network were also having issues (not the case this time) I thought it was the router and replaced it. That solved the problem until a couple days ago. Glad I found this thread and will try the "aluminum hat" fix if it comes back!

I have been struggling with this problem for two days. Brand new MBP 2016 with touch bar. Top of the line 13".

Initially I was using an AUKEY vga hub with 4 usb ports. My wifi would drop to a crawl when the hub was underneath my dell monitor. Also, the monitor was jumping around and the Phase/Pixel Clock would not fix it so it wasn't jittery.

I resolved the problem a bit by moving the vga/usb hub to the opposite side of the desk away from the monitor. This allowed for internet access, but still not as fast as the speed without the hub plugged in.

Also, upon a low battery, when the computer tries to wake from sleep with this hub plugged in, the computer malfunctioned to a point where i could only see the pointer as well as notifications.

After a trip to the apple store (where i spent several years working, leading the sales floor) chatting with my good buddy who is now the genius admin, we determined that it could be a power management issue. Once the laptop had enough power, it was able to figure out its display settings and could view my desktop again.

MAINLY... to resolve this thread issue, I purchased a Belkin usb-c to vga. This adapter has no other use. It has no usb plugs nor does it have a usb-c input that may cause any interference. I now have a clear picture on my monitor and absolutely no wifi issues.

my opinion is that while the technology is suported for the usb-c to handle multiple tasks through one port, it can be overloaded and really hinder the performance of the computer. Try avoiding a hub if at all possible to test my theory.... worked for me, but now ill be carrying a bag of usb-c adapters.

This worked for me too!

Late 2013 Retina Mac Book Pro, Dell P2715Q @4k, and Ubiquiti Router.

This configuration had been working fine for the past few years, the issue just started today (-2 hours!!). Changed the router frequency to channel 1 and it came right.

Wifi was either dropping most packets or not connecting at all. Narrowed it down to the monitor connected with Thunderbolt/DisplayPort and then google found this post.

I had the exact same problem. Some how it started after I upgraded to the latest OS version. Tried everything and nothing worked. I thought it was my tv blocking the signals so tried to put the range extender, still no good. Came across this post and found changing a channel might fixed. I changed the channel from 6 to 2 and it started working. Now I can have monitor connected and still can access wifi/internet. So happy.🙂🙂🙂

Problem on old and New.

I had this problem om my 2011 early Macbook. It broke so I bought the new 2017 Macbook, the stupid one with only 4 USB 3.1 ports. One would think that they would have fix the problem in such a new and expensive computer. But no, it's still there.

Today I discovered that my WiFi drops whenever I plug in ANYTHING (except the charger) through the thunderbolt/usb 3.1 ports. I kinda makes make computer rather useless.

Here is a list of possible sources of interference. http://support.apple.com/kb/HT1365. See bullet 7 which relates to monitors.

I am experiencing the same problem on macbook air 13'' 2010 and macbook pro with retina display mid-2012 . When I plug external monitor to thunderbolt port through hdmi adapter, my wifi connection drops. OS X Lion on both.

I am getting this issue with a Macbook Pro retina with Lion. When I plug monitor into another computer the wifi is fine. As soon as I connect to thunderbolt the wifi instantly disconnects. It's as if the thunderbolt port is draining the power from the wifi interface.

I might add I have a 2nd monitor in the HDMI port which doesn't intefere with wifi.

There are tonnes of forums with these complaints out there. I have tried some of the advice, like changing wifi channels and buying an Apple made mini displayport adaptor without any success. And now I am wondering the same thing as raysian. If the problem is simple interference with the monitor why does my wifi work perfect when I am not plugged in but beside the monitor (the monitor is on not in sleep mode) yet instantly drops when I plug into the monitor? The problem seems to be very big as it is affecting many generations of macbooks.

Very similar issue here:

Brand new MBP Retina + DELL 2007 FP monitor, connected via a ~ 2 year old Apple Mini DisplayPort to DVI adapter. Extremely slow WiFi traffic or even problems connecting to WiFi. No matter which of the two Thunderbolt ports, no matter wether the laptop is open or closed.

Everything is working fine as soon as the DELL monitor gets unplugged.

Not sure if Apple's interference statement is really valid as my old ThinkPad T60 shows no WiFi problems at all at the same time and same place.

I managed to fix it by changing wifi settings on my asus wifi-router. I have changed channel number to 1.

Same problem here.

BRand new mbp retina with apple thunderbolt to dvi adapter. Once i unplug the display wifi works good.

Very big issue for me.