You're setting up your Sophos as your local DNS server, and then want to have your Sophos get its answers via DNS over TLS? As far as I know, SFOS doesn't support this yet.
It's on their to-do list. Sophos has their own DNS service which uses standard IP addresses. They need to get DNS-over-TLS support in the firewall, soon, before customers get angry.
But now I suppose the secure DNS that's built into Windows and in most browsers will have to do for now.
This feature is currently not available on SF. Kindly reach out to Support to have it requested. You may mention idea SFSW-I-970, and it can be linked under your registered Sophos account.
Thank you for your time and patience and thank you for choosing Sophos.
