If you want to speed up your internet speed you’ll find all kinds of articles talking about DNS. If you’re interested in that please check out https://www.makeuseof.com/tag/change-dns-increase-internet-speed/
I’m just interested in getting a forward resolver up and running as quickly as possible. The quick solution: dnsmasq.
To install dnsmasq on a Debian 9 server it’s as easy as:
apt install dnsmasq -y
The service should already be running
service dnsmasq status
Now you just need to configure your client devices on your LAN to use that DNS server.
For 1 device just change the DNS settings for that device to point to the IP address of your new DNS server using the RFC1918 address that’s been assigned to it.
For multiple devices the DNS settings should be configured as part of the DHCP server to hand out the new set of IPs that includes your DNS resolver as the first option such that it prefers that DNS resolver unless it becomes unreachable and then continues on to the next one.
Need details on dnsmasq? Excellent post here: https://www.linux.com/learn/dnsmasq-easy-lan-name-services