Would Like To Use my Time Capsule as my Main Router Instead of my NVG589

I have a Mac Mini server running the latest version of Mavericks and server app version 3.2.1. When I first signed up for AT&T U-verse I had a 2Wire 3801HGV modem. I was able to set up web hosting using the server app and Phusion Passenger for my Ruby on Rails applications running Lion Server. Even upgrades to Mountain Lion and Mavericks did not mess up anything. Everything worked as before.

A few months ago all my U-verse services quit working well. The wiring was updated to CAT-50. My modem was changed to the Motorola (Arris) NVG589. Now web browsing is slow at best and my web hosting no longer works. Either my websites do not display at all or they display with no images. I assume the DNS is set up properly for the web hosting because the correct websites show up. I did a clean install of Mavericks and put the same DNS settings as I had when everything was working. I also did a Server Hardware Test just in case something was wrong with my hardware, especially the memory. No problems with the hardware were found. I came to the conclusion the problem is with the NVG589 modem.

I did some web searching on the AT&T site and others and found that the problems I describe occur with the NVG510 and the NVG589 because of a known software bug where the DNS check times out really quick before most websites can display. The only option I have (I guess) is to make my Time Capsule the main router. I found a solution in several places, including the AT&T forum.

I have two questions regarding this:

1. It was suggested that if the Device IPv4 Address is the same subnet as my personal router's LAN segment that I should change the subnet on my personal router (aka Time Capsule) to something like 192.168.10.0. How can I change this number in Airport Utility (or some other tool)? I could not find a way to do this.


2. The steps also say to disable the section on the NVG589 where I opened ports 80 & 443. I know that theses ports are already open on my Mac Mini server. How do I open them on the Time Capsule? Right now I am in bridge mode at the advice of an Apple specialist while trying to solve another problem long ago. When I change the router mode of the Time Capsule to DHCP will I be able to open ports using Airport Utility (or some other tool)?

If I cannot resolve this I have lost my development server where I need to be able to test my websites assigned to a domain before deploying to my production server. I checked the AT&T website and the only modem mentioned for AT&T U-verse is another modem that looks similar to the one I have. Maybe it will work but I just wonder.

Any help would be appreciated.