Trying to connect WHR-300hp2 router to CM1000 modem

[Cuddlefish]

Hello,

Trying to set up a Netgear CM1000 modem to a Buffalo Airstation WHR-300hp2. The old setup has a motorola modem without a username or password. The fancy new Netgear modem has a username and password, which I set to something other than the default.

After connecting the router up, I cannot get a DHCP address from the modem. If I plug in the ethernet cable from the modem to my machine, I can browse.

I tried making sure the gateway was correct (192.168.100.1) adding the modem username and password to PPPoE settings, and increasingly desperate attempts to get things to work.

Am I overlooking something? I'm not sure if there's much I can change on the modem side apart from the password, but I wonder if it's in some mode that isn't working with the router, or if I need to set something up on the router. Please advise.

Thanks in advance.