AOSS (AirStation One-Touch Secure System) is how the Nintendo DS securely connects to Nintendo Wi-Fi. To my knowledge a problem with this should be in your router or whatever you are using for your Wi-Fi connection. I am pretty sure that standard internet providers don't block these types of signals, so what you should do is look into your routers setup. You can either try simply resetting it (unplug power for one minute) or you can actually go into the router admin panel. This is pretty simple, find out what brand the router is and then google this: "brand name here" IP address. it should give you something like 192.168.0.1 but all brands are different. Once you get there it will probably ask for a password, this will NOT be a WEP but and admin password. If you have never set that up, simply type admin into the user and leave the password blank and hit ok. This should bring you to whatever control panel the router has. You can look around for some sort of AOSS setting that for some reason might not be enabled.
Nintendo provides this
to help you set up an AOSS connection on a router, also if you find the brand of your router google to see if it is AOSS compatible.
Hope this helps