Hi i recently start working as admin in small company contains multiple offices , they had about 20 computer 

first thing I notice many employees figure-out  how to changes DNS address on their windows machines t use Google 8.8.8.8 DNS server 

this alow them to bypass websites restriction that the company had set (streaming/adult sites)  , the internet line aren't  that good either 4MB , most of all offices suppose to use the internet connection to browser certain website (fill application ) and download emails, that's it .

until now I could not find away e.g to redirect dns queries  that sent to Google dns to other server the router uses ?

please tell me if this possible with this router 

here is the router Emulator page 

https://emulator.tp-link.com/EMULATOR_wr840nv4_eu/index.htm