Hi,
It would appear that you have three possible sources of DNS addresses, the CGN2, RT-N66u and finally the laptops. Question is, which one is supplying your DNS address, and has something happened to it that you are not aware of?
Looking at the CGN2 Manual page Page 48 Figure 12, you can enable the CGN2 to use your selected DNS address when the DNS box is checked, or use Rogers DNS by leaving it unchecked. So, if you do nothing, you end up using the Rogers DNS. The assumption here is that you have the CGN2 in Gateway mode.
REF: http://setuprouter.com/router/hitron-technologies/cgn2-rog/manual-1028.pdf
Looking at the manual for the RT-N66u, there is only one space for the primary DNS address. Given the lack of instructions in the manual, it would appear that if this is blank, then it uses the DNS address of the IP provider, which in this case is Rogers, if you have elected to leave the CGN2 DNS fields empty. If you input an address into the N66u DNS address field, you have to reboot the N66u for the change to have effect.
Lastly, there are the laptop settings. I bring this up as there was a case very recently of an erroneous DNS address in the pc or laptop. You have to drill down to the DNS address settings to determine what is set, Automatic DNS address from the router, or manual DNS address that you have selected. Here is the link to the Microsoft page that describes how to get there:
http://windows.microsoft.com/en-ca/windows/change-tcp-ip-settings#1TC=windows-7
So, by reviewing all of those DNS sources you should be able to determine what device is providing the DNS address. To confirm that, open a command prompt and type:
IPCONFIG/ALL
That will display your ethernet parameters including what DNS address is actually being used. With that you can compare the address against the contents of the CGN2 or N66u address fields. Here are the fields from all of the displayed IPCONFIG/ALL data on my pc, which shows the OpenDNS addresses:
DNS Servers . . . . . . . . . . . : 208.67.222.222
208.67.220.220
From what I remember, I think there have been issues with DNS addressing from Rogers. I don't use Rogers DNS so I can't personally confirm that. A food for thought consideration is to put the DNS address in the pc and laptop so that in the event that your router is hacked and the DNS is changed without your knowledge, you will still be using the DNS address from the pc or laptop.
So, have a look at the DNS address fields in the CGN2, N66u and pc/laptop and see what turns up. Let us know what you find out.