I think what's going on is that your DSL provider is only letting 1 device connect at a time. Which would be why you all can't be connected at once. Normally having a router on one end will fix that little problem, the fact that your DSl modem has a built-in router kinda throws a kink into the problem.

I've typed up several things, erased them and now recommending you find out more information.

1. You've got a DSL modem that has built in router functions. You need to connect to it and find out if that stuff is turned on or not. By default it is.

2. You've got an AP you can't connect to, which means that the DSL modem probably assigned it a different IP address, in which case, you need to disconnect the AP from the DSL modem and reset back to default settings so you can connect to it and find out what's going on with it's settings. Or you can open a command prompt window.. and type

ipconfig

I believe the address appearing under default gateway will be the wireless AP. Try putting that address into the web browser and see if you can log into it.
Username:Admin
Password: (leave blank)


3. Download the DWl-700AP manual from D-Link | Welcome It has a nice tutorial for setting it up.

Let me know how it goes