Airport connection problems with lid closed

[allanj37]

I just got one of the new (April 2010 version) 15" macbook pros. The problem I'm having is that the airport basically stops working if the computer's lid is closed (it's connected to an external monitor). I'm still getting 5 bars of signal, but it's having problem talking to the router. Pinging my router with it open results in about 3-10 ms for every ping. With the lid closed, about a third of the pings time out, and the rest take anywhere from 5 to 2500 ms.

According to ifixit, this version of the macbook pro has the wifi antenna next to the cd drive opening instead of the screen -- so the position of the screen shouldn't be affecting the wifi reception. Through my own testing, I have also confirmed that the position of the screen doesn't make any difference. If the screen is open even the slightest amount, it works fine. But as soon as it's closed, the problems start happening. This leads me to believe it's some sort of software problem.

Is there anything I can do to fix this, or am I just going to have to wait until Apple releases an update?

Update: I'm starting to think this is a hardware problem -- see my post below for more specific testing results.

 

[miles01110]

Is there anything I can do to fix this, or am I just going to have to wait until Apple releases an update?

Considering Apple doesn't intend you to run the machine with the lid closed, you could be waiting a long time.

It still seems to me that it would be at least somewhat hardware related, though. When the lid is closed the wifi antenna looks like it'd be fairly well shielded.

 

[RobbieTT]

Considering Apple doesn't intend you to run the machine with the lid closed, you could be waiting a long time.

Why do you say that? Apple calls this 'Clamshell Mode' and lists it on its support site complete with instructions.

Eg:

http://support.apple.com/kb/HT3131

 

[aristobrat]

Is there anything I can do to fix this, or am I just going to have to wait until Apple releases an update?

All of my MacBook Pros (three original styles and my current first-gen unibody) have acted like that.

The difference with WiFi performance between the lid open/closed is like night and day.

I have an 15" i7 MBP on order. I had hoped to hear the new antenna placement would have helped this problem, but it appears not. I run my MBP in clamshell mode 90% of the time, connected to a 24" Cinema Display + bt keyboard/mouse.

 

[miles01110]

Why do you say that? Apple calls this 'Clamshell Mode' and lists it on its support site complete with instructions.

Eg:

http://support.apple.com/kb/HT3131

That's a good question Maybe they will offer a fix. I'm going to go put my foot in my mouth. See edit above, though.

 

[allanj37]

I just did another ping test (100 pings to my wifi router). This time it only lost 11% of the packets, and the average round trip time was 75ms. I tried browsing the web, and it was definitely slow and choppy, but it did at least load pages eventually.

So it seems that the problems are more intermittent than I first suspected.

Incidentally, the results with the lid open also improved over my previous test. This time none of the pings took more than 3ms.

 

[allanj37]

It still seems to me that it would be at least somewhat hardware related, though.

After doing a bunch more tests, I'm starting to think you might be right. For each of these tests, I used the network utility to ping my wifi router 50 times and recorded the percent of packets that timed out and the average round-trip time for the packets that did make it. I also tried some simple web browsing just to get a general feel for how slow it was in real-world terms.

The results were extremely variable -- the computer was in the same position with the same programs running for each test, so I'm not quite sure why this is. In general, the closer the screen was to being closed, the worse the performance got. The closest I could get the screen to closed without it snapping shut was 1/4 of an inch. At this distance, it was almost as bad as if the screen was closed completely. At half an inch to three quarters of an inch, the internet was typically at least usable. By the time it was open a full inch, the slowdown was completely unnoticeable for web browsing.

This indicates to me that something about the screen (or the rim around it) is interfering with the wifi antenna. You'd think Apple would test something like this before releasing a new product -- especially after moving the internal antenna around for this model.

Here's the data from my tests:

closed
28% lost
228 ms average

closed
28% lost
1362 ms average

closed
48% lost
524 ms average

closed
18% lost
471 ms average

1/4" open
20% lost
736 ms average

1/4" open
28% lost
168 ms average

1/2" open
12% lost
71 ms average

1/2" open
14% lost
25 ms average

3/4" open
22% lost
51 ms average

3/4" open
0% lost
8.4 ms average

1" open
0% lost
10 ms average

1" open
0% lost
7 ms average

all the way open
0% lost
3.5 ms average

all the way open
0% lost
3.3 ms average

 

[allanj37]

I figured out a fix for the problem! I switched my network channel from 1 to either 6 or 11, and the network works perfectly with the lid closed. I switched back to 1, and the problems returned.

So does anyone have any idea what's going on here? Is the screen somehow blocking or interfering with that one specific frequency?

Oh well...at least I can use my laptop in clamshell mode now.