Cloudflared stops resolving DNS.

I am not sure how to diagnose the issue but hoping someone can help. Not overly sure if it is an issue with Clouflared.

I have successfully setup Cloudflared to act as a DNS server and using it with Pi-Hole. I have manually specified my DNS on a laptop and that works perfectly.

Unfortunately is I change my DNS in the router Cloudflared stops resolving DNS. I have double checked this by connecting using SSH and manually attempting a DNS query and nothing is returned. It stopped working immediately after changing the router to hand out the DNS server.

The steps taken to setup closely follow: https://scotthelme.co.uk/securing-dns-across-all-of-my-devices-with-pihole-dns-over-https-1-1-1-1/