I am. Server IP is 192.168.1.xxx. DNS server is running on that machine. It already allows access from all interfaces. I just don’t have port 53 natted from my router to avoid creating an open resolver.
Look into Pi-hole. It’s an easy-to-setup DNS server which can run on a Raspberry Pi (or a Linux desktop/server if you have one.) You can then set your devices’ DNS servers to the local address where the Pi-hole is running. Since it would be running on your local network, any requests to it shouldn’t go through your ISP in the first place. I’d still recommend getting your own router anyways because this kind of ISP fuckery is more common than you’d expect. Plus, your exact configurations follow you anywhere you move. If you do end up getting one, set the local DNS server in the DHCP settings of your router to avoid having to set it on each device.
Just wanted to let you know I somewhat found a solution and edited my post to reflect that.