System Error Message
Part of the Furniture
i see what you mean, its definitely a hacked router as the DNS server on the PC was BT and the response wasnt. It just means someone hijacked the DNS from the router which is a feature some routers have. Checking the PC could help, the must've gotten in somehow. I suggest using something like shodan to scan your IP and see what is visible.You need to look at your PC and see which DNS it is using. IF it uses the router DNS then the router was changed. If it is using a DNS server on the PC then your PC was changed. If you use a local DNS then it could have been changed.
One other thing to check is your host file. It is possible it was changed on the PC. More than likely it was your router.
I still dont recommend cisco RV. I would never recommend one even if cisco gave me their blade servers used in T1 ISP routings for free which can do many Tb/s of layer 3 and probably layer 7 too.