In the router settings page go to Advanced then select firewall (some other routers show IP filtering under Advanced tab you just have to look for IP filtering) as in the picture?
Open the firewall level drop down list & choose custom then name it google then submit it
Now choose the firewall level you just created named google then from the options under choose IP filtering
Click on new then go down & enter the same exact values in the picture below then click submit
Repeat step number 4 but with google's second DNS 8.8.4.4 like in picture below then click submit
