As you may have noticed I've been posting a few questions about some problems I was having while setting up a custom DNS Server (using AdGuard Home for ads and trackers blocking) and now I reached to another problem related to IPv6. A bit of context of my whole setup for this: I have a Synology NAS running Docker. I have a Docker container running AdGuard Home (the DNS Server). I have two subnets, one is the main network the other is the guest network. The guest network cannot access any client on the main network with the exception of the DNS Server and even for that, only port 53 is allowed. The Synology NAS has an IP address of 192.168.0.99 (main network). The DNS Server running in a Docker container has an IP address of 192.168.0.253 (main network). The DNS Server Docker container has it's own IP using the Docker MACVLAN network driver. With Docker MACVLAN networks, the host (Synology NAS) cannot access the containers (DNS Server) and to get that working I have a MACVLAN interface in the host itself (based on this guide). In my Tomato router dnsmasq configuration, I push the 192.168.0.253 DNS Server to all clients in both the main and guest networks. I also have IPv6 properly configured on my Tomato router and my main Windows machine. On my main Windows machine, the network connection is both configured with IPv4 and IPv6, using the AdGuard Home DNS Server for IPv4 but using my ISP's DNS Servers for IPv6. Now, what's my problem? Windows will pick either the IPv4 or IPv6 DNS Server and if I'm not mistaken will give priority to the IPv6 one, only using the IPv4 one if needed. This is a problem because for this particular Windows machine, the AdGuard Home DNS Server won't be used that much. Which brought me the question, should I even be using IPv6 on my Tomato router and my Windows machine? Should I just disable IPv6 on the router and forget about this? Or should I take the time to configure my AdGuard Home container, MACVLAN networks, firewall rules and all that to work with IPv6 too? Do I have anything to gain from using IPv6?