AOSS is for connecting other Buffalotech products to Buffalotech products. It also works with Sony AOSS enable playstations.
When you try to connect a third party device to a Buffalotech product set up with AOSS, it can get more complicated, usually with the password.
For mixed mfrs, you may want to use WPS (Wi-Fi protected setup - the same button as the AOSS button), but your client will need to have WPS as well.