Cable and WAP

no, the WAP will not work that way. You should make it a wireles router and then you'll be in business.

<i>It's always the one thing you never suspected.</i>

I'm not really following how your setup but an AP is just a wireless hub. It will forward packets sent to it to associated clients. You say Modem connections(s). I've never seen a modem that had more than one connection. Some of them have both ethernet and USB interfaces but only one can be used at a time. Sounds like your modem might have built in LAN ports and and is also a NAT router. If you have an open LAN port on whatever the device is your talking about then yes, you can use your AP, this assuming you have an available IP to hand out. The AP might be setup as a DHCP client so if you only have one IP to hand out then the AP would nab it so you might consider connecting to it first and disabling it if it does. If you can explain how your setup a little better I can give you a definitive answer. If you can use a hub or switch in the port your talking about then you can use an AP.