You should never need an "install CD" to do anything with a router. What brand/model is it? In Mac OS you can find the router's address by doing "netstat -rn | grep default" in a terminal. You can then browse to the address found to access configuration.
The ISP's router/modem theoretically shouldn't interfere with AC client, but I have had many odd issues including ones with AC caused by those devices' firewalls, so disabling them is always a good test.
The ISP's router/modem theoretically shouldn't interfere with AC client, but I have had many odd issues including ones with AC caused by those devices' firewalls, so disabling them is always a good test.