Hi. I have successfully tested one method, but it is not perfect. It has been tested on windows 7. The idea is to connect the motorola modem using usb cable to one computer (i.e. a desktop computer). This computer must be kept turned on(change the power settings for not to get in sleep mode). Then share internet connection from desktop computer to the DSL-2730B dlink router using ethernet cable to port 1 for example. You could connect another computer using the other ports by ethernet cable. Here is the complete procedure:
1.USB CABLE DRIVER. Download the usb cable driver for sb5100 from motorola http://broadband.custhelp.com/app/answers/detail/a_id/21177/session/L3RpbWUvMTM2MzY1NzQwNC9zaWQvSUE2TTN3bGw%3D
I recommend the 2.4.7.1 version for sb5101 modem.
2. INTERNET SHARING CONFIGURATION. Connect the usb cable to the desktop computer, and set up the Internet Connection Sharing. In the adapters network section, choose your usb network adapter, properties, internet connection sharing and select both option, it is possible the system will ask you about changing automatically the ip address of the ethernet adapter from dynamic to static. Check the correct change of the ip address in the ethernet adapter to 192.168.137.1 . It is easier setting up the internet sharing configuration using this desktop computer and a laptop computer using crossover cable. The laptop computer must have dynamic ip address assignment. Test the internet connection in both computers and then disconnect the laptop computer, (I think it is not neccessary using this laptop computer, it just made me the setting up of the internet sharing configuration easier).
3.CONNECTING THE ADSL ROUTER. Connect the desktop computer to the adsl router using a regular ethernet cable in port 1 (It doesn't matter connecting to port 1 or port 2, even doesn't matter using a crossover ethernet cable).
4. ADSL ROUTER CONFIGURATION. Because you are going to make changes in the parameters of your adsl router is a good idea to reset this adsl router (pressing for 10 seconds reset button, the power light turns red, and then restart adsl router). Now you can access to configuring your adsl router by using a internet browser. Two ways: Accesing from desktop computer (ethernet connection) or laptop computer (wireless connection). In the address bar type 192.168.1.1, your username admin and your password admin . The next procedure coud block your access to 192.168.1.1 therefore all the following steps must be done without rebooting or unplugging the ethernet cable in your adsl router.
a-Create/enable the required number of wifi connections and their respectives passwords in SECURITY TAP.
b-Disable wan firewall in WAN-SERVICE-EDIT
c-Disable DHCP server in LAN setup.
d-Disable upnp
5. SETTING UP WIFI INTERNET CONNECTION. At this moment restart adsl router. If you want, connect another computer to port 2 of the router. If it still not working interchange the ports 1 and 2, and restart adsl router.