Q: Internet connection problems

I have recently purchased a new iMac and have had a problem intermittently with the wi-fi symbol being greyed out and unable to connect.  If I unplug the iMac and the router (they are both on the same electric plugs) and then re-insert them everything is okay when I switch on again.  I have been on to the online help and a lady guided me through all the settings and was surprised that the DNS number was the same as the ip address.  She said it should begin with a 209 number.

At this I rang my broadband supplier (Sky) and a man gave me a number beginning with 207.  I filled this into the DNS number space.  The wi-fi was on but the internet didn't work.  I rang Sky again and another person told me that the DNS number should be the IP number.  This I entered and I can now access the internet again.  Do people in these call centres actually know what they are doing?

Anyway, has anyone any advice as to what to do if this problem happens again?  The second person I spoke to at Sky seemed to think the problem is with the apple iMac rather than the internet settings as other computers in the house do not have the same problem.  Maybe it is this iMac which has some fault.

Any advice would be most welcome.

Anne Adshead