Dual monitors causing wireless drop outs on MacBook Pro running Lion

I have a 13" 2011-model MacBook Pro running Lion that I connect to a Dell monitor.

The connection is made as follows: mini DisplayPort -> mini DisplayPort to DVI-D adapter -> DVI-D into monitor.

Everything works quite well graphically when I connect the laptop to the monitor, but it pretty much instantly causes the wifi to slow to a trickle.

This wifi trickling happens every time I connect to the external monitor. As soon as I unplug the connection to the external monitor, my wireless is restored to full power and I can connect to websites like this one.

Is there anything I can do to troubleshoot this very annoying problem?

Here's what happens when I switch from single monitor to dual while pinging 8.8.4.4:

64 bytes from 8.8.4.4: icmp_seq=14 ttl=56 time=30.070 ms
64 bytes from 8.8.4.4: icmp_seq=15 ttl=56 time=30.886 ms
64 bytes from 8.8.4.4: icmp_seq=16 ttl=56 time=31.343 ms
64 bytes from 8.8.4.4: icmp_seq=17 ttl=56 time=31.772 ms
64 bytes from 8.8.4.4: icmp_seq=18 ttl=56 time=30.662 ms
64 bytes from 8.8.4.4: icmp_seq=19 ttl=56 time=162.196 ms
Request timeout for icmp_seq 20
64 bytes from 8.8.4.4: icmp_seq=20 ttl=56 time=1071.753 ms
64 bytes from 8.8.4.4: icmp_seq=21 ttl=56 time=417.013 ms
64 bytes from 8.8.4.4: icmp_seq=22 ttl=56 time=478.626 ms
Request timeout for icmp_seq 24
64 bytes from 8.8.4.4: icmp_seq=25 ttl=56 time=367.057 ms
64 bytes from 8.8.4.4: icmp_seq=26 ttl=56 time=443.585 ms
Request timeout for icmp_seq 27
Request timeout for icmp_seq 28
64 bytes from 8.8.4.4: icmp_seq=29 ttl=56 time=365.072 ms

As you can see, soon as I switch to dual monitors, the return time drastically increases, sometimes timing out completely.

Any ideas?

Solution 1:

Looks like I accidentally stumbled across a solution: if I move my laptop an extra 30cms away from the monitor, the internet connection doesn't trickly away to nothing.

It's probably some kind of interference that is causing the problem, and it seems that keeping some distance between the monitor and the laptop is enough to resolve the issue.

Solution 2:

Switch your wireless access point to a different channel!

I had the exact same problem on a mid-2012 MacBook Pro with Mountain Lion. The Apple cable would give me errors on the external monitor, so I bought a 3rd party one that worked perfectly but killed my Wi-Fi connection. Switching the Wi-Fi channel from Auto to Channel 10 somehow solved this issue—works perfectly now! (Didn't figure this out myself, someone suggested it on some forum, but I don't remember who and where.)

Solution 3:

My 15" Macbook Pro Unibody used to drop all WiFi connections immediately when connected to my external monitor. I was ridiculous, I would have to disconnect my external monitor any time I needed to access the web. Fortunately, I found a solution.

Answer: Use an Apple-brand Mini-display-port to DVI adapter instead of a RocketFish brand adapter. Now I have wifi AND my external monitor, all at the same time.

Solution 4:

I have a similar problem. When I take my MacBook to the 1st floor of my house, the connection becomes very unreliable, extremely slow. If I try to disconnect and reconnect it fails to reconnect to the access point. The access point is placed in the basement, so the signal has to travel through 2 floors. Just as you, the wireless strength indicator indicates that I have a strong signal.

This used to work perfectly fine. But I can however see that there are now a lot more wireless networks (+10) than there used to be. So I assume that the problem is caused by interference from from my neighbors' wireless connection.

So perhaps if you can place the access point closer to your work desk, it could solve the problem.