I had Mullvad’s DoH endpoint hardcoded in a router config and in a boat-side Pi that only sees wifi when we’re docked. That’s the failure mode: the thing you set once in 2022 and never look at again dies quietly on November 2nd 2026, and you debug it three weeks later wondering why nothing resolves.
So grep your configs tonight, not in November. Mullvad Browser on defaults migrates itself, but manually set variants — base, extended, family — stay stuck on your value, and iOS/macOS profiles just stop working. Swap those for Quad9’s. The larger lesson for anyone self-hosting: an upstream deciding it’s better to fund the specialist than duplicate them is a good decision that still lands on you as maintenance.
The story — Mullvad is shutting down the public encrypted DNS (DoH) servers it has run since 2022 and financially supporting the Quad9 Foundation instead, calling it the undisputed leader rather than duplicating its work. Mullvad VPN users are unaffected since internal DNS handles queries. Manual DoH configs must switch before November 2nd 2026; Mullvad Browser defaults migrate automatically; existing iOS and macOS profiles will stop working. (Source)