question : connection error hokuyo 30LX EW

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I am trying to connect hokuyo 30LX EW to my labtop

I have installed Ubuntu 14.04 and ROS indigo in my labtop.

when i type rosrun urg_node urg_node _ip_address:="192.168.0.11" *ipaddress was already changed in window system.

the error occurs, could not open ethernet port.

1. I am now using laptop with wifi, when I connect the ethernet port it seem like crushing each other? is it the problem?
2. I am going to connect 2 hokuyo lidars (same model), please give me lots of advice to solve this problem

thanks in advance