Two rows: DNS resolution from host rig and phone through AdGuard to an upstream DoH resolver, and the admin UI reached only through Caddy and Authentik SSO

One DNS Filter, Three Clients That All Bypass It Differently

I wanted a DNS sinkhole in the lab — block ads, trackers, and adult content at the resolver instead of per-device. AdGuard Home is a single Go binary, so standing it up was maybe ten minutes. Then I spent the rest of the session learning that “point a device at the resolver” is a lie three times over. A Windows PC, an iPhone, and the lab host each route DNS somewhere I didn’t tell them to, for three completely different reasons. This is the write-up of finding all three. ...

1 August 2026 · 7 min