Home wireless network help!

Question

Ok... So I recently moved to a new house, and moved my Internet service. Im with AT&T and I had DSL. I was supposed to have next day installation because I work from home and take classes from home and every day I go without Internet costs me money. However, they told me that DSL was not available in my area. I ordered Uverse and I ended up having to wait a week and a half for them to install that, only to find out that the couldn't because the cable box is too far away from my house... But they said I could get DSL. Anyway, long story short, it's been two months, I had to drop two classes which has cost me almost $3,000 alone, and I haven't had any income because I can't work.
I have Internet now, however the way AT&T set it up mean i had to get a new modem. My old set up involved a 2wire router/modem connected to a time capsule in bridge mode. It worked like a dream and I was able to have my laptop, desktop, ps3, 360, wii and two iPhones connected to it all at once with no problems. Now I have a motorola modem connected to the time capsule. All of my devices are detecting my wifi network, but non of them can connect. The ps3 times out trying to obtain an ip address, the phones connect to the network but continue to use 3G, and my laptop gives me the "another device is already using this ip address" message.
What do I need to do to get everything up and running again? I'm sick of typing and browsing with my iPhone and not having Internet. In my case time really is money... Anything any of you can offer to possibly help would be greatly appreciated....

Answer 1

Resetting the Time Capsule back to factory defaults will not affect your backups in any way, as the reset only affects network configuration settings, not the Time Capsule disk.
I'm not sure if you will be able to make much progress without an internet connection, but if you want to try, here is the sequence of events:
If it's not already, connect the ethernet cable from the modem directly to your Mac
Open your browser and type in 192.168.1.254 into the address bar and press Enter. This should bring up the modem configuration pages, which you have already seen.
Click on the Advanced tab/label on the left
Click on the PPP Location tab/label
Select the option for "PPP is on the computer (router)"
Click Save and the modem will restart with the new settings
Important...if you ever need to return the modem back to its new, out of box configuration, hold in the reset button on the back of the modem for 8-10 seconds, then release. It will restart with original default settings.
Connect the ethernet cable from the modem to the WAN (circle of dots icon) port on the Time Capsule.
On your Mac, open Macintosh HD > Applications > Utilities > AirPort Utility
Click Manual Setup
Click the Internet icon
Connect Using = PPPoE
Enter your user name (probably your email address with the provider) and password. Confirm password.
+Important...leave the Service Name area completely blank+
Connection = Always On
Disconnect if Idle = Never
Click Update at the lower right and the Time Capsule will restart in 25-30 seconds.
You may need to restart both the modem and Time Capsule again. With no internet connection, you won't be able to test for connectivity, but when the service comes back on, you should have an internet connection on the Time Capsule. Post back on your progress.
You will probably need to reset Time Machine to get backups going again as follows:
Open System Preferences (gear icon on the dock)
Open Time Machine
Click Select Disk
Click your Time Capsule to highlight it
Click Use for Backups