I figured it out.
Login to your router that has the OpenWRT firmware installed.
Click System, Software, the letter L, and install "Luci-app-dnscrypt-proxy".
A new tab will appear next to "System" called "Services".
Click on "Services" and choose "DNSCrypt-Proxy".
Click on the "Resolver...
How do you use adguardDNS with OpenWRT?
The router has a place for IPv4 addresses and just below it there is a place to enter IPv6 addresses.
https://imgur.com/KrfpVCG
When I google "what's my ip", google tells me my IPv6 address, but when I go to ipchicken.com, it gives me my IPv4 address...