Inspiron N5040 Wireless connection is lost

Dear Dell Expert,

I need an advice on problem that started few months back. My wireless adapter will not see one of the bands generated from my Cisco router and will connect only to one (the weaker one)! More recently it started not seeing it or connecting to it only to cut the connection later. Ironically the same adapter is seeing my neighbors wireless connections!

This problem was before I purchased a proxy capable of over the net calls. Both shows on the ipconfig that I ran after the doing more basic things that didn't work.

If the adapter is not seeing anything, I would directly take it hardware store and replace it, but since it does see my neighbors, I presume it need reconfiguration.

PS I have Bitdefender installed on my laptop (anti virus known to slow down things plus maybe other things, and also the proxy I mentioned. I can email the ipconfig if needed as I cannot make much of it. But I cannot see attachment enabler. 

What is the solution?

Regards

Sam