Stop it injecting 1.1.1.1 into DNS settings

I'm running a pair of Minis, provisioned with Immortal, in test harness. (no Facebook account).

no matter what my router is giving out over DNS, it always seems to add 1.1.1.1 as a DNS server.

This is mainly a problem because local DNS records on my two configured piholes are returning NXDOMAIN if Cloudflare responds first.

does anyone know how to remove 1.1.1.1 from the DNS? it's driving me nuts and I can't figure it out.