FaceTime fails with "WiFi Connection Lost"

Question

My Google skills haven't found any matches for this, but perhaps others have seen it in passing at least.
I've noticed recently that I've been having problems with FaceTime calls to a friend of mine. For the past month since he got his iPhone 4, he'd end up losing the WiFi connection, but now it's happening to me, too.
The symptom is that the FaceTime call will be going fine for a while, and then it will just hang with no motion in the picture from the other phone for about 10 seconds, then the phone will beep and display this error:
FaceTime Failed
WiFi Connection Lost
<OK>
At this point, I find that my WiFi indicator in the status bar is gone and replaced with "3G". It has indeed lost its connection to the WiFi access point (a Time Capsule).
Going into the iPhone's settings, I see that it shows there that it is still connected to my WiFi network (showing a checkmark next to my WiFi network name, although it still says "3G" at the top). Cycling WiFi off and back on corrects the problem.
My friend is also using his iPhone 4 connected to a Time Capsule, so we have similar setups. I'm beginning to wonder whether there's some problem either in iOS 4 or the Time Capsule that causes the wireless connection between them to disconnect in an aberrant fashion.
So, anyone else seen or heard of this?

Answer 1

FaceTime connection problems on my iPad2 was magically solved by changing the DNS number (in the Settings > Wi-Fi menus) to:
208.67.222.222, 208.67.220.220
(yes, there is a space after the comma, and a space after the numbers 7)
I recommend that you write down your present DNS number for safekeeping before you make this change.
I hope this solves your FaceTime connection problem!
All the best,
Brad P.