Open the telnet port:
http://<RouterIP>/setup.cgi?todo=debug
Then telnet in to the IP. Tada!
Simple as pie.
Once in type ifconfig...
Depending on your router you will get a series of adapters appearing
Like
"br"x --- A bridge between wireless and ethernet
"eth"x --- Ethernet connection
"lo" --- local loopback
"ppp"x --- Dial in iburst connection
"nas"x --- wireless connection
Let me know what you see.