I have the exact same problem. This is INFURIATING!
Moreover, it's extremely vexing. Here are the facts as I blogged them on my blog:
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I am unable to get to webex.com since I set up the Time Capsule. At all. I don't want to have to send the Time Capsule back, but I will if I have to.
But this is a very vexing problem, and here's why:
1. I cannot get to webex or any webex site (like v.webex.com my company's webex site) from my MacBook Pro over Wifi, neither using Safari nor Firefox.
2. I cannot get to webex from my MacBook Pro with a wired connection either.
3. I cannot get to it from my iPhone over Wifi.
4. I can get to it from my iPhone over 3G.
Naturally, this leads me to believe it's a problem with my network, and since the only thing that has changed is the Time Capsule, I have a very likely suspect. But...
5. I can get to it from my wired Windows Vista computer.
Which naturally makes me suspect some apple-related issue. But...
6. I can get to it from Jill's iMac over Wifi.
So in review, I know it's not a Wifi issue; it's not a wired issue; it's not an apple issue, it's not a router issue. The only two ways I cannot connect are on my iPhone over the Time Capsule and on my MacBook Pro over the Time Capsule. The only logical conclusion at this point, the only thing these two device connection have in common, is me. My own home network hates me.
7. And now, to further prove it out, I have circumvented the Time Capsule and connected to Webex using my Sprint aircard. I can connect over the aircard.
Now the only logical conclusion at this point is that Time Capsule hates me. That or I'm caught in the crossfire. Maybe webex hates Time Capsule or Cisco hates Apple or vices versa, and I'm the cat getting kicked.
No matter what the result's the same. I can't get to webex.
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Final thoughts. I just set up the Time Capsule today. The first two devices I connected through it were my MacBook Pro and my iPhone--the two devices that are getting hammered by the Time Capsule. If my memory is correct, the next thing I did was set up Time Machine on my MacBook Pro and begin backing up the whole hard drive. I think these were the only two devices I connected before setting up Time Machine. Does the TC have incorrect cached routing information somehow for these two devices?
Whatever has happened, there is definitely some connection between the TC and these two devices. It is an evil connection.