Issue with ZyXEL router EMG3425-Q10A

Hello there, I recently got service from Ting, a fiber internet provider. The EMG3425-Q10A was the router that they provided with me when I purchased their service; after poking around a bit and familiarizing myself with the router I pointed the DNS servers to openDNS's name servers so that I could continue using their web filtering services.

I've put the DNS settings both under the WAN settings and in the DHCP server settings as well but the issue is that the router will, after a random period of time, stop using them and I can access blocked sites (porn, etc). I'm using the OpenDNS Updater and it notifies me whenever I am no longer being routed through their servers. I've contacted my ISP about it and they don't feel the issue is on their end.

Has anyone else had any similar issues or can point me in the right direction?