This may help picture the situation in series. Trace the route to umn.edu from my home desktop: iznogoud at bigpapa:~> traceroute umn.edu traceroute to umn.edu (134.84.119.107), 30 hops max, 60 byte packets 1 192.168.0.1 (192.168.0.1) 10.194 ms 11.361 ms 11.557 ms 2 192.1.0.1 (192.1.0.1) 12.180 ms 12.380 ms 13.147 ms 3 stpl-dsl-gw11.stpl.qwest.net (207.109.2.11) 27.331 ms 27.768 ms 31.007 ms 4 stpl-agw1.inet.qwest.net (207.109.3.81) 31.311 ms 31.733 ms 35.064 ms ... The first 192.168.0.1 is the D-Link WAN. The second is the 192.1.0.1, which is the modem+router LAN, and this is also the gateway address of the D-Link's WAN. The D-Link's WAN has an IP like 192.1.0.2 or something like that. Say the WAN of the DSL-model+router dies. The D-Link will have the 192.0.1.* link dead, but the 192.168.0.* network will work just fine. All your computers will live in that network and will work fine.