HOWTO: turn a Motorola SURFboard into JUST a modem (and not a wireless router)

Introduction
If you've ever had one of the Motorola SURFboards then you know that it is not just a modem but a "Wireless Cable Modem Gateway." This means that the Surfboard plays the role of the modem and the (wireless) router. However, as with anything that tries to be all-things-to-all-people, it has its shortcomings. Among them is slow or dropped service when many people are attempting to access the internet at once through the wireless.

An easy fix for this is to buy another wireless router to put in front of the SURFboard. However, this presents its own problems. You want your new wireless router to play the role of the router, but the SURFboard already thinks that this task is its job. This could easily mess up your port forwarding settings, and sometimes prevent you from getting any access to the internet through your new router what-so-ever.

The solution is to get your SURFboard to behave only as a modem would and turn off all of its routing functions. Here's how you do it.  I have only tested these instructions with Motorola SURFboard SBG901, but I do not see any reason why this would not work with other SURFboards.

Instructions
(Note: do the following before you connect your new router!)

1. Log in to the SURFboard
   Unless you have changed any setting for your SURFboard, point your browser to 192.168.0.1 and type "admin" for the user and "motorola" for the password.
2. Turn off the wireless
   Click the "Wireless" link in the top navigation bar.  Now in the drop down field labeled "Wireless," select "Disabled."  Click the "Apply" button.  (See Figure 1 below.)
   

   

   Figure 1

3. Disable NAPT mode
   NAPT (Network Address Port Translation) also known as NAT (Network Address Translation) is the work that your router does in figuring out which data goes to which device.  If NAPT is enabled on your SURFboard then it will perform the task of routing data before it hits your router.  This could have unintended consequences, such as misrouted or dropped packets of information.  If you disable NAPT on your SURFboard, it will simply pass the data through to the router (this is the behavior that we want.)  To disable NAPT, click the "Basic" link on the top navigation bar.  Now in the drop down field labeled "NAPT mode" select "Disabled."  (See Figure 2 below.)  Click the "Apply" button.  Your SURFboard will now restart.

   

   Figure 2

4. Set up your wireless router like normal
   Follow the instructions provided with your wireless router.  

After the set up, SURFboard should be functioning as a modem only and the wireless router should be performing all of the routing functionality.