Some versions of Windows have an "only connect to known networks" feature. Here's a link on that. But maybe this is overridden by Asus's app?
"Ensure that 'Automatically connect to free wifi hotspots' is unchecked." moves around the windows interface. I can't guess where is on your PC.
More at https://www.google.com/#q=windows+only+connect+to+preferred+wireless+network
Hey guys having some trouble with my connection as in it always connects to a BT fon network when i start up my pc, i have tried removing the network through the network and sharing center but when i shut down my pc and load it back up it always connects to the same one, i'm using a asus dual band network card and have the perferences set so it connects to my virgin media super hub on the 5G channel.
Can anyway help me? Its not a massive pain because i can just connect to the correct one its just annoying that's all.

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