@Toke 

Hi,

How have you established that it is not working? Just by looking at the front page of the router?

To verify that the settings you've made under the "LAN Settings" menu are working you need to check on your client devices.

On an up-to-date Windows 10 you can go to Settings -> Network and Internet and on the status page click the Properties button for the active network connection.

On an Android device you may have to install an additional app (for example AIDA64) to show addresses of things like default gateway and DNS.

I can't help with iPhone / iPad devices.

By the way, no matter what DNS address you setup on the router, the user of the client device will always be able to manually configure another DNS address if he or she wishes to do so.

@woozle i did check multiple clients and they do state the RPI's ip as the DNS. I've checked on adblocker test sites to verify it's not working. I figured it was a matter of the router settings as the configurations looked very different from older versions of my router, but I may be wrong.

Since the clients are using the pi as a DNS I guess it's got to do with the installation of Pi hole.