About a year ago, with help from AT&T tech support, I set up a SpeedStream 4100 DSL modem to work with my linksys router. They had me connect my PC directly to the modem, reboot, and browse to 192.168.0.1 to enter name and password information into the modem. After things were set up, I was able to connect my router's WAN port to the modem, and let my router assign 192.168.1.x addresses for PCs on my home network. But, even after doing this, I could still get to the modem at 192.168.0.1. My net mask is 255.255.255.0, and I'm trying to understand why I can still get to the modem. I wouldn't think that 192.168.0.1 would be on my subnet, but if my router is relaying the request to my gateway router, how would it know about my little DSL modem at 192.168.0.1? Is the modem doing NAT for it's LAN address? Is that how it works?