New open-source tool: DnsAutoSwitch, a Windows service in F# (.NET 10) for AdGuard Home / Pi-hole users whose DNS box isn't always on.
Windows doesn't fail over between DNS servers deterministically, so a secondary DNS bypasses your filter. DnsAutoSwitch keeps one DNS server and switches it: primary while it answers, router when it doesn't. Hold/pause files, logs. MIT, release zip, no runtime needed.