Hello glen.sasahara,
Thanks for using the Cisco Small Business Support Community. I'm sorry to hear that you are having trouble accessing the internet from WAP connected devices, and I hope that we can help you find a solution.
The Asus RT-N66U device is a router, which by default, functions in "router mode". Are you remembering to set the operation mode to "Access Point(AP) mode" on the Asus device?
Connecting two routers in series can cause routing problems, which may be the problem in your case if you didn't set the Asus device to "Access Point(AP) mode".
Please reply back with any additional information and we will do our best to help resolve your problem!
If this post solves your issue, please remember to mark your question as resolved, and rate any helpful posts to help other members in the community! Thanks!
I hope you will find this answer useful.
Ruben