This sounds as if the new modem has a built in wireless router capability. Connecting another router to the mix is not likely to work. Why the need for two routers?
I used to have just a dsl modem and a netgear wireless firewall router working together properly. Now I have a new dsl modem with wireless capability which works fine but I want to use with my netgear wireless firewall router and i can't get it to work. Any suggestions anyone can provide would be great. I've gotten as far as having all the green lights on the modem working appropriately when connected to the router but that configuration cant seem to log on to my service.

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