The Apple Internet Router is an AppleTalk-only router. It will not route any other protocol, including TCP/IP.
The Apple Internet Router AppleTalk/IP Wide Area Extension provides a method for tunnelling AppleTalk traffic between two AppleTalk routers across a TCP/IP-only backbone network segment. This is accomplished by encapsulating AppleTalk packets inside of TCP/IP packets. The IP Wide Area Extension does not route TCP/IP, it rather provides a way to join AppleTalk LANs using a TCP/IP wide area link.