Wi-Fi dropping

[#1]

I seem to have a recurring issue with  wi-fi. The connection was lost about 09.00 this morning and has not returned, unless we take a laptop and sit next to the router. The diagnostic suggests that there is too much wi-fi interference, even though I also use a wi-fi range extender
Fortunately I have powerline adaptors, that enable me to connect via ethernet cable.
I am wondering, is this purely an issue with wi-fi interference, or is my router [Technicolor 582n] to weak or at fault somehow.
Any ideas?

[#2]

you could try changing the wireless channel
Forgive me if you know these steps
Log into the routers GUI
In the left hand column click on Home Network then
in the top of the new page click on the WLAN:Plusnetxxxxx
on the new page in the top right click on configure
in the new page make the changes as required then scroll down and click apply

[#3]

You can use something like inssider to see how many wireless channels are in the area and which channels are the best to use:
http://www.metageek.net/products/inssider/

[#4]

inSSIDer is now a paid for app.
For a free version go here http://www.majorgeeks.com/mg/getmirror/inssider,1.html