AOS = Avast Online Security - this is a browser extension / add-on for most common browsers (IE, Firefox, Chrome, etc.). This should have been automatically installed along with the latest Avast! version (for IE and FireFox; for Chrome, a web site should have opened after the installation reboot and asked you to install the add-on).
To change the firewall connection type, go to Settings > Active Protection > Firewall > Network Profiles and select the drop down box (Profiles - Public / Private). Also (if you are changing from a Private to a Public) you want to uncheck the Friends setting.
How did you connect to the AccessAnywhere service before using Avast?