As far as I know there are no specific AirPort diagnostic utility, either provided by Apple or any third-party vendors.
Drop-outs, on wireless network, typically are associated with Wi-Fi interference that is preventing your 802.11n AirPort Express Base Station (AXn) from providing a clean RF signal. It may just be that someone else has just started operating a Wi-Fi network or installed a portable phone system that is operating on the same radio band and channel as your AXn.
I suggest you perform a simple site survey, using utilities like iStumbler, or AirRadar to determine potential areas of interference, and then, try to either eliminate or significantly reduce them where possible.
Thank you for your reply. I've installed iStumbler and will watch to see what it shows if the dropouts continue.
I have a follow-on question, if you don't mind.
In the iStumbler display, my network shows with a level of only about 70-72%, dropping to below 50% occasionally. May laptop is sitting less than a foot from the Airport Express unit. How can the signal be so weak at such a short distance. As I write this, I see a level of 49% for my network (802.11n) and the next strongest is an 802.11g network from a router across the street at 25%. I'm on channel 1, it's on channel 11. There are some closer routers in my building, but they show less than 20%. Any ideas?
Is there something that might be running on my system causing this? ATM, the only user apps running are Camino, Safari, MS Word, Mail and iStumbler.
To get a more accurate picture of your wireless network's signal quality, use the Inspector feature of iStumbler to review the raw Signal & Noise values instead of their percentage values. We would want to do this to calculate the Signal-to-Noise Ratio (SNR). SNR (in dB) = Signal (in dBm) - Noise (in dBm). You will want this value to be 25+ dB or higher for decent performance from your wireless network.
To access the Inspector, go to the iStumble menu bar, and then, select Edit > Inspector. Select the Samples tab and use the mouse to stretch the window so you can see all of the Inspector columns.
Now jot down some of the Signal & Noise pairs, and then, plug them into the SNR formula above. Please post back what you find for your network with your laptop sitting near the AirPort Express.
Ok, this range of SNR is excellent as it should be at this distance. However, the wide swings does tend to indicate that there are some form of RF in the area that introduces Noise into the environment. I would then think both of your wireless clients would have increasing difficulty with maintaining a good connection as the distance between the client and the base station increases.
Since you have an "n" version of the Express, you may want to consider configuring it to run on the 5 GHz radio band which (at present) has less congestion. If you perfer to stay on the 2.4 GHz radio, I would recommend that you, at least, change the Radio Mode to: 802.11n only (2.4 GHz) to prevent any non-"n" clients from connecting and lowering the overall bandwidth to support them.
Turned out to be my wireless phone is the culprit. We had a brief power outage last weekend, which is when this problem started appearing. Apparently when the phone restarted after the power came back it picked a channel that ****** on my airport, which was set to automatic on its channel setting. Didn't make the connection until I was using my iPad and my wife made a phone call. iPad, iPhone and MacBook all lost their network.
Within moments after my wife hung up, network was back.
I've hard set the Airport to channel 10 for now, since that seemed to be least populated of all the wireless nets in the building.
I'd rather set it to 5 GHz but the iPhone and iPad don't seem to see that. Not sure if they should be able to or not. Will have to search that.