Hey guys, anyone had the same problem and solve this? 

Can't call method "recv" on an undefined value at  C:/Users/[name]/AppData/Roaming/Oh My Git/net-test line 23.

Thank you everyone for help. 

You might have a local process already bound to port 6666. You can find out which process by entering the following into a Command Prompt window:

netstat -ano -p tcp|find "6666"

If you get a hit, the final number should be the Process ID (PID) which you can cross-reference in the Details tab of Task Manager.