IChat, Airport and Motorola surfboard modem

Question

Hi all,
I cannot get iChat to work with a particular buddy after moving to another city with another Cable ISP.
I use an airport extreme basestation and have a motorola surfboard modem SB5120. The airport extreme is configured to connect to the internet using DHCP and both my iMac and iBook are configured to connect to the base station using DHCP. I've connected to this buddy succesfully every time on my old network using these settings.
What I tried...
I cannot work with static IP's because my ISP only works with dynamic IP's.
I've deleted com.apple.ichat.plist... No effect!
The motorola modem is not configurable in its html interface. My ISP however assures me it doesn't block ports and lets all traffic come through.
Quicktime streaming: automatic... iChat: no bandwidth limit
However...
Configuring the airport base station to not hand out IP adresses, is a FIX, but off course the iBook then cannot connect to the internet.
AND... when i DO configure it to hand out IP adresses and try to connect to several testadresses posted elsewhere in this forum (not just the Apple ones) i connect every time.
I don't know what is wrong, but it has me glued to my iMac for a week trying to come up with a solution. I've even combo updated my iMac with all firewire devices disconnected. I'm DESPERATE. .
Thanks in advance for your highly anticipated advice.
Greetz,
Rob

Answer 1

I have a simular modem and set-up.
The set-up is as follows:
Cable Modem <--> AEBS <--> Switch <--> Mac/Vonage/other pc/AE
I have all of my Mac/PC set to a static IP address (You configure each MAC/PC with a different IP address 192.168.1.100, 192.168.1.101, etc) Your DNS servers are required anytime you go with a static IP address. You can find out your DNS server by launching the Airport Admin Utility and clicking on network. The numbers will be greyed out and not in the normal white box that is listed.
Router should be 192.168.1.1
That should get you on the internet.
Next while your in Airport Admin, under internet confirm the following:
Connect using: ethernet
Configure: Using DHCP
IP address: (should be listed)
Subnet mask (should be listed)
Router address: (should be listed)
Next, click network and distribute ip addresses should be checked along with share a single ip address (using dhcp & nat) using the 192.168.1.1 addressing.
Next, under port mapping - map the following ports to your primary machines ip number (mine is 192.168.1.100)
5060,5190,5297,5298,5353,5678 as public ip address 192.168.1.100 and private as 192.168.1.100
If all that checks out, you have the same setting as I do with a very simular modem and I can connect with both PC and MAC users with no issues.
Does this help?
P.S. If you setup is the same as me and you still have issues, I had a friend that it was necesarry for him to call his local ISP and they made a change to his IP addressing-then all worked fine.