Well my first reply is: setting up yor own router is like to learn driving with a touring car. You just need to know a lot to set up/handle everything properly. Its just not easy and in m opinion the most wrong point to start.
DNS-wise I would like to recommend something like pihole. To me it was my first thing I installed and used until this day and also the handling of DNS is quite easy. Maybe you should consider lerning other things before setting up your own router.