Hi Gopal,
1) Please check from your laptop whether your IP address of your modem is pinging or not.
2)Don't specify port number in sap logon pad.Specify router string like //75.72.180.164//
and try to connect.
If it is not connect paste the output of error.
3)Check whether router string is running or not.
4)check the log file of dev_rout in saprouter file.If any data is there paste here.
5)paste the command which is used to run the router.
Regards,
Patan Thavaheer.