If changing the DNS servers were the only change you made, this should have no affect what so ever on accessing your server via IP address.
I recommend you attempt to restart your router, and failing that, perhaps a restore as something else must have gone wrong.
I would also advise you double check the address of the router.
Just to double check - whilst you say the router is at 192.168.1.1 - are you accessing it via that (http://192.168.1.1) or are you just saying that is the router and are you attempting to access it via a name (such as http://router) - if you are doing anything other than the IP, try via the ip!