NetworkManager defaulting to Wireless

[Armelius Cameron]

Hello,

I have a fresh installed F12 on my machine. For some reason, the 
NetworkManager always prefer to connect to Wireless network rather than to 
using the ethernet connected cable (System Eth0). Even when before turning on 
the machine, I already plug in the ethernet cable, after logging in to KDE the 
NetworkManager still picks the wireless connection. I have to manually 
disconnect from wireless, and choose System Eth0 everytime to use the 
ethernet.

This happens both on my work campus, which has open wifi network for visitor, 
and at my home network with WEP. On the workplace it would connect to the open 
wifi, at home, it would prompt me the Keyring manager and then connect to the 
wifi, both time with cable plugged in to it.

I tried to search on Google, and look at /etc to find out where I can change 
this behavior, but haven't had any luck.

Several other laptops I set up with F12 for friends do not have this problem.

Thanks for any help.
AC