Linksys BEFW11S4 Router Networking issue

I never come across a problem like this before... I got one of those linksys router. I have Verizon DSL at home, I am trying to connect 3 computers (all under Windows XP pro). If I plug in the modem's ethernet cable to my router's upload port it won't work. When I connect one computer directly to the DSL modem, I realized that its a private IP address, 196.168.1.xxx given by Verizon. So I guess I have to configure my router to act as a switch/hub. Its a 4 ports router I can only get the router to work ONLY if I connect the DSL modem's patch cable to the 2nd port in the router (the rest will not give any connection). Then I can connect all 3 computers on port 1,3,4 and they will work. And the upload port will not be connected. Does anyone knows why this is happening? And why only port 2 will work with my DSL modem? Thanks

That was what I though, before I posted this message I changed 192.168.168.1 but it didn't help. Did not solve my problem. even if all my computers are connected with the 4 ports without using the upload port, none of them can see each other on the same network, even they are on the same workgroup.